Whatever time is needed, 3 seconds, 5 seconds, 7 seconds, 10 seconds, 15 seconds, as long as you can. It doesn't matter at all to me because...

I HAVE ABSOLUTE CONSISTENCY WITH MY SMOKING TECHNIQUE NOW.

The whole this is that YOU MUST INHALE DEEPLY.
I was smoking over 30mg and it was flooding over a tiny portion of my lungs and nowhere close to all of it being absorbed and getting no OEVs, no CEVs, just a tiny psychedelic buzz
Now, as I have experienced previously, as it should be, 10-15mg inhaled deeply through to each and every alveoli possible and I am in a significant 2+, nearly 3+ experience.
(tested 5 times in the past 24 hours to make sure)

Thanks for the replies in this thread and it's indirect but very important role in leading me to that discovery.

(Haha, I write all poetically after smoking DMT )

Sorry, I didn't see the last post...

Glad you found a way that works for you. We hashsmokers know that if you want a good hit, is helps to truly empty the lungs and then bring your dose into them with as little air as possible, then fill your lungs with fresh air. There's little point to holding a hit forever when you're holding it in your throat and the very top of your lungs. In fact, the last quarter or so of a large breath only serves to pull the air in the airway into the lungs, so make sure you save it for pushing the vapor that last leg of the journey. (That is, if you want to journey)

Yeah, if you smoke it like a girl smokes a cigarette you'll have lots of problems. I'll add "bring the smoke into your lungs" to my new traveler tutorial. Glad you find a way to guarantee liftoff with the GVG. I love it!