I.G.
There are some pretty neat preschool programs in daycares, I really liked the ones my DD attended and they did have part time kids just coming a few days a week in the morning. Since they are year-round there is no particular start time.
If that isn't an option where you live also look into preschool summer camps. DD attended a few weeklong summer camps last year (usually one week long, just mornings from about 9AM - 1PM) as an alternative to her year-round daycare and had a blast.
Good luck.