"I want my first dmt experience to be vaporhuasca"
You probably don't. You didn't really eat 12 feet of cactus, did you? You mean 12 inches I suppose. I think 12 feet would be unpleasant to say the least.
If the maximum dose of mushrooms you've done is under two grams, you may be surprised by the intensity of dmt alone. I've seen people who had their first experience with vaped dmt combined with oral harmalas. One was so traumatized, she has sworn off psychedelics forever. She had done 5 gram doses of mushrooms on top of LSD in the past. She said that those were like a cup of coffee compared to her dmt/harmala experiencer. Do not take this lightly.
Who knows, it could be okay, but I would suggest trying it by itself first, unless you are going to be vaping tiny amounts over a long period of time. Even then, I would try a solid dose of only dmt first.
Welcome Home Mister_Niles. We've Been Waiting For You.
"Don't worry. When it happens, you won't be able to not let it do its thing. You won't have the ability to distinguish a pen from a hippopotamus"
- Art Van D'lay