If you are going during spring break, there really is no "good" time to go--- it is GOING to be CROWDED! You will definitely want to take advantage of fast pass and early entry. Don't wait until afternoon to go to the parks. Get to the gates about an hour early and stand there and wait. If you can be one of the 1st through the gates, it will definitely give you an advantage. Also, if you don't need a stroller, or even if you do, line up to the left side. The lines are often shorter. Then, if you need a stroller, send one person in your party to get it, and the others go into the park and line up for an attraction... plan a meeting place.