Morning Work outs are great! but can be hard. I can get in the routine for about week of moring workouts til i default back to evening. typicaly though its not due to lack of will it's holiday or morning tasks that get thrown at me last minute that makes me skip the morning and work out in the evening.
usually if i get up and work out, it helps if i didn't work out too late the night before, if i had to skip the morning prior. also, just typical common sense, go to bed 8 hours prior to the time you want to get up. even if you have to lay in bed awake for a bit before you sleep.
it's great that you're doing P90X, it's awsome. I'm on my second round of 90 days (day 114 of working out, no skipping) What ever you do don't skip a day of work outs, it's harder to got back to working out everyday than it is to make time in the evening if you miss the morning.
Life is now! why waste it.