I am incredibly skinny, and MDxx always hits me WAY before any of my friends. I am in biz in about 20 minutes, no joke, and it is not psychological, that's how everything hits me. Also, I descend into the plateau quicker than most of my friends, but I never say quit until much later in the night.
Another thing is when I eat food, I get hit with energy literally minutes later and am hungry all day. Either I have a 100lb tapeworm, or my metabolism is cracked out.
So either 100lb tapeworms or increased metabolism must shorten the amount of time it takes to start rolling.
And when it comes to tobacco, I found that organic hand-rolled tobacco is an excellent thing to smoke while rolling. It is an ancient prayer/meditation technique to smoke tobacco, and recent studies indicate that almost all of the adverse health effects attributed to smoking cigarettes stems from the pesticides, fertilizers, and additives, (and agent orange's own dioxin) not the actual smoking of the plant itself. There is exposure to tar, and combusting anything and inhaling the carbon monoxide laden smoke is bad for you, but most cancers are probably attributed to impurities.
I always link to Mike Adams articles, so just ignore me if you don't care about life and health.
http://www.naturalnews.com/034744_tobacco_leaves_genetically_engineered_cigarettes.html
http://www.naturalnews.com/008291.html