Here's a summary of my first experience:
I felt pretty prepared mentally, despite the fact that I haven't done any psychedelics since about 1998. (!) But back in the mid 80's, I took a LOT of LSD, mushrooms, and even back then some things like 2cB & DET. But back then, we didn't "have the Internet" and other than a Biochem grad student (who made the 2CB) we didn't have access to the chemical mileu available today.
Getting things going: I found less success with the ash sandwich method. I suspect this is because of how I've done this sort of thing before, with another chemical free-base. With that, you get it melted in a glob and it's caught in the screen and boils vaporizes off as you kiss it with the flame. I burned quite a bit of DMT.
So, the pipe I used is maybe a sort of "baby" knock-off of a Vapor Genie. I made a stack of "more screens that you think you might need". I put four screens in there. This way once the DMT melts, it gets caught by the lower screen(s) and can liquify/bubble/vaporize in there, and the flame can come right down near the top screen after you get going. If the flame does happen to touch the top screen--after you get the DMT melted and down past there, you haven't scorched/burned the DMT. I got much better hits that way, with the particular pipe I used; the size of the bowl and the "draw" through the pipe makes it hard to get the right temperature with just 2 screens and the ash sandwich, without burning things. (since then I've gotten a GVG...totally worth it)
So I had tried initally with small (approx 15 mg) amounts to get a feel for the pipe. With that, I just got the roaring in my ears, strange colors, a little clumsiness and edginess in my body, and the "typical" "introductory" visuals you get with a low dose of LSD or mushrooms.
So for the breakthrough, I'd loaded up approx 45 or 50 mg in my four-screen-no-ash setup. Here's how it went:
Music: Orbital, the song IMPACT to start off.
I take one good long, slow, gentle hit. Fill my lungs and hold it. hold it. Exhale partially, inhale air, hold. Exhale a bit more, inhale air, exhale. Good hit. A bit of rushing in my ears. Whoa, a bit edgy, shaky. Better do another hit now before I forget. I get even more this time. Wow. Better put this pipe down. Getting kinda shaky & clumsy. Seeing some weird colors. Lean back. The music sounds really great. Ah, there are the Patterns, coming on fast. I'm vibrating. I lay back 'cause I worry I might fall over if I don't. I hope I don't forget to breathe. Heh. I won't.
I see what I decided to call the Window. It's not really like an actual window, it's the mandala irridescent stained-glassy-like trippy pattern that "converges" once your typical psychedelic patterns get going good. You've seen tons of descriptions (and pictures!) before of things like it. Interesting to me that so many of us see the same sort of thing. Even in different cultures.
The Window starts out small, then the shapes in it get more complex, brighter, and the whole thing gets "bigger" or "nearer". This is happening really fast.
Now I'm really close to the Window and I can see "in" or "behind" it. Behind it there's a space where things are moving. Things that make the Window look like it does when you're on the "outside" of it. There are little guys I decided to call the Workers or the Helpers. (are these my version of the "elves"? They crank gears, so to speak--but there are no true gears; they move things, beyond/through/in the window. I'm at the edge, now. The space in there is big, and I'm now in it. Parts of the moving shapes, flows, and structure occasionally have a Worker in, on, or around them. They're distinct from the environment. I have forgotten my body. I'm in here. It's funny: these guys I get glimpses of, they smile knowingly, like we share a secret.
They look really odd, the closest I can explain is something like Curious George crossed with a Sock Monkey if Sock Monkeys didn't look stupid, mixed with a bit of Trollface from a rage comic. Hard to explain. Are these the guys other people talk about? I don't know.
I'm pulled further in/down/through this space, and the Helpers are rushing by, around, (acros & through?) me and the patterns of the space are "big" and they're shifting and twisting.
Now, I see what's making the larger framework move. Something manipulates this space at a larger scale. There's energy at a macro level. It's a being that looks really odd. It's something like an octopus. But without suckers, eyes, or a mouth. It's bigger than I am. I feel like it's a He. All the Helpers were male too, come to think of it.
He doesn't have a definitive number of tentacles--but he always has exactly as many as he needs.
The tentacles shape, route, move, and steer all the objects as well as the light, sound, and "space" in this space. He's doing things.
He reaches out/over/up to me and I feel my hands, arms, and face twist and pull "flatter". Weird. He continues the manipulation and then I'm being pulled flat, along my axis. Head to toe. How does that happen? Snap!
Whoa--I'm 2 dimensional! WTF? Yep, definitely 2-dimensional. Infinite width and depth available here, but no height. Octopus is here too of course (how the hell can I explain a 2-d grey octopoid?) and hes moving and guiding me around. At some point, he rolls my eyes "up" (which somehow works--there's not any way to properly explain, as there's no "up"

and I can see the other spaces that intersect this one, and we "pop" out into them, where again he's steering, pulling, guiding flows of ever changing matter and energy all around, in, out, up, down, and through.
I note that I'm feeling electrified, although the edges are fuzzy and grainy, and not entirely aligned with the shape/inside/outside conformation of my physical body. Hmm. That's weird. I find myself feeling strange. the shock-flow seems to be drawn out of me and into the Octopus. For an instant I think, "is he taking something out, or away?".
Then. He replies. Without sound or speech--but telepathically:
"It's good. It goes in AND out...Feel?"
I do feel it, then. The flow is as much in as it is out. It goes around and through as well. Everywhere. He says now:
"You see? It's all One."
And I do see. I know. It's all One.
(And friends, we've hit the Jackpot. My ticket to the transcendental experience has been redeemed...)
It's an incredible feeling. An incredible Knowing. Octopus continues guiding, steering, and manipulating the flow. The "landscape" of this space continues to roll, twist, wave, turn inside out. We slide. In some places I begin to see the helpers, near the edge; the Window is becoming visible. I'm back to where I can feel my body now and am willing to control it. I might move my hand or open my eyes. I perhaps could have at any time, even while I felt 2D, I knew that the body was "available"; but that didn't matter. Things are strange when I open my eyes, like you'd feel on a mushroom trip.
I notice that I'm saying over and over, like a mantra, "It's all One". Hmm.
When I close my eyes again I see (of course) that I'm at the window now. I've moved through it, "back" past the Helpers. They're now on the "other side" of the Window; I know they're there, but I can't see them now. The window gets further away (the patterns are smaller). It looks like a stained glass mandala with metallic iridescent panes (like peacock feathers). The panes move or split, grow or shrink, but it's getting farther away.
I'm now aware of what middle part of the song is playing (it's a 10 minute song).
I've stood up, and note that I really feel gravity. So, this is what it feels like to have weight. I'm talking to myself, aloud, saying things that need another post to cover. My dog has come over to me and leans against me while I pet her. "Hello, my 25-thousand years old wolf-friend", I say. I really see and feel the incredible length of time her ancestors and mine have been together as friends. "It's all One," I tell her. She doesn't seem surprised.
The trip slowly unwinds. We're at about a "five hours into one hit of acid" level and lessening minute by minute. I still smile and find myself looking at things and saying softly, "It's all One." I'm not gonna forget that, man.
Communicating telepathically about the nature of reality with an octopus-like, eyeless, mouthless, as-many-tentacles-as-he-needs creature that manipulates and guides flows of energy--that was worth immesurably more than the effort to "get there".
If you haven't broken through yet, & you're willing to make the transition, we can be in unity, constancy, and peace; because it's all One.