If you want to find a cheap flight to Florida the best time to look is outside of school holidays that means avoiding travelling at the busiest times. These are Christmas, Easter Time and the school summer holidays spanning mid - June to mid - August.
One of the best times to fly cheaply would be late May or early June - just before school holidays start. However, be sure to avoid travel in and around Memorial Day as you may find prices are slightly higher at this time. You may also be able to grab a cheap flight to Florida in the summertime for yourself at the end of August, just before the new school year starts.