I did this the very first time I tried mescaline.
I had made an extraction from san pedro, but 2½ hours after ingestion I still couldn't feel a thing so I assumed I have done something wrong with the extraction, so I dropped 1½ g of fairly strong mushrooms.
Within 10 min I was absolutely blown away...
Everything I looked at formed patterns. I went for a walk with my sitter as I couldn't take being inside. I drifted in and out of visions, one moment being in a cathedral and the next I was back with my friend.
I have never been anywhere near as fucked as I was there, but it was a positive experience. Never has the world been so beautiful and fascinating.
"First hour's all waiting, and then about halfway through second hour. You start cursing the creep who burned you because nothing's happening. And then... zang!"