If the clover is Strong - I suggest

1. Memorial Day (late May) - reduces annual weeds and some grasses
2. July 4th ( delays early seeding of clover heads)
3. Labor Day (late Sept.) - ensures clover remains dominant and promotes lush growth for October bow season.

These are days we can all remember - and at least in the Northeast - work out OK.

If you are in a drier climate - you might Skip the 7-4 mowing.