i don't think it is so much about the ammount of spice you smoke. this happened to swim's friend with a small pipe hit of 30mg or so. as for swim, he goes for the 1 hit bomb (90-120mg) and it takes just a couple of seconds to enter the dmt realm.
i think it is more likely for someone to feel sick before the hit (utter anxiety and the jitters) than during it though.
"..undisturbed by order, chaos creates balance. it is not the artifical balance of scales and weights, but the lively, ever-changing balance of a wild and beautiful dance. it is wonderful; it is magickal. it is beyond any definition, and every attempt to describe it can only be a metaphor that never comes near to its true beauty or erotic energy."
"the angel is free because of his knowledge, the beast because of his ignorance. between the two remains the son of man to struggle."