Down here in La. the "best time" is Sept-Nov at the beaches, but there are flounder to be had all summer long if the conditions are right. The best nights are when high tide is at it's highest point while it's still dark during the week of the new moon. For example - if high tide was predicted to be at 9pm - I would hold off on the trip - but if it was at 3am I would make plans to go----and flounder from dark until high tide (3am). Flounder "move up" into the shallows with the high tides, feeding on baitfish at the shoreline and then retreating back into deeper water when satiated. I usually make 3-4 one-hour trips during the rising tide at the same location waiting for them to feed. Sometimes, I have seen them so close to the shoreline that you'd swear that they were on land! When they show up it's a blast!