One of the keys to my success has been that I make a calendar, and stick with it. For me, one of the major reason I was stuck in the fitness doldrums was that I took far too relaxed of an approach to my schedule.
I, like many people, would go to the gym, warm up on the treadmill for 10 minutes, and walk around for an hour looking for machines to use with very little rhyme or reason to what I did.
That all changed last March when I began P90X. I had a schedule, I had a plan and I stuck to it. I tweaked the P90X schedule so that I had Yoga X on Saturdays (it is 90 minutes long and was far too long to do in the mornings before work). I stuck to the schedule and had really good RESULTS.
With my first round of P90X2, once again I decided to start off by sticking with the calendar. The only small change I made was moving Yoga to Saturday mornings. I love having yoga on Saturdays, it just feels like the perfect way to end a week and kick off the weekend.
I think what days you do which workout is less important than having a plan. I know myself. I know that if I came downstairs at 5:15 am, and had to make an on-the-spot decision about which disk to throw in, I would cop-out and pick the easiest one, every time. It is my natural inclination to revert to the path of least resistance, it is just how I am wired. Knowing this about myself (know thy self, right?) I go into each 3 month round of P90X, or whatever, with a plan. I create the calendar ahead of time I know, not guess, but know, ever day what I am going to do. I have tapped into to some other RESOURCES for helping me create hybrid schedules.
Making a calendar, and sticking to it has been one of the most important keys to my success with at-home workouts.