I'm weird, in that I can keep rolling for up to 10ish hours (once I felt effects for 12...no e-brag).
But I would suggest you take your first dose at the rave, then hit the second dose as you are peaking, or very shortly after you've peaked. That should give you the best combo of longevity and quality of roll.
I typically like to double drop, and then pop another pill or pill and a half about 2.5 hours after my first dose (but I take forevvvver to come up). That's enough to keep me in a really good place from 9ish pm till around 5 a.m.