You can do all 3cc's, make sure you fill slightly above the 3cc line tho. Also your ass will be more sore, massage area for a couple miniutes afterwards and push it in slowly so some will absorb and allow room for it all, you will have a knot no doubt about that. If you do 2 shots in a day just use the other cheek, and dont plan on sitting down to much the next day or so, when I do 3cc's of test-200 my ass is sore...
Peace