If you have something that prevents LO from napping at his "normal" time several days a week, what do you do the rest of the week?

Basically, we are looking at preschool that would meet 3 days a week from 1230-3. I am wondering if we muddle through those three days however we can (no nap or late nap) and then go back to his regular 1pm-3pm nap the other 4 days, or stick to our changed schedule of no nap or late nap, regardless of whether he has preschool. Thoughts?