Leving at 9 a.m. (depending on where in SD you are) could get you to Disneyland before 11, whch may leave enough time in the park for you (and since it's in May hopefully you won't spend a lot of time getting parking, buying tickets and standing in line for rides). I certainly wouldn't want to leave Anaheim before 8 p.m. on a weeknight, anyway, due to traffic.