This time of year is typically when southern and gulf flounder begin their spawning run. Now, there are a few triggers to the bite but I truly feel that wind direction and water temperature are 90% of it. Post cold front conditions being a cool or cold North East breeze of 10-15 mph, water temperatures of 72 degrees and dropping, emerald green water with a light chop are my preferred conditions. The presence of large schools of finger mullet doesn't hurt either. I find that tide has little to do with the fish's feeding activity but everything to do with their location.
The fish will move between tides on the slack and take up positions in depressions in the bottom once it's roaring. That being said, it goes without saying that it is a rocky, not sandy bottom, that best serves as a staging area. Your looking for broken bottom in 1-4 feet of water. Look for the fish to be laying between the largest rocks or in the sandy holes scattered throughout the area.
I find that the biggest fish actually prefer to hang out in the heavier current. Flounder are built for ambushing prey in fast water. The current keeps them down, making it easy for them to conserve energy. Heavy current also makes it harder for small prey to maneuver. Simply put, if you want big fish, fish the current. Smaller fish tend to stack up in slower, sandy areas.
The first and last push of flounder of the year are frequently the larger dominant fish. Targeting them means being patient and utilizing baits many might consider to large. My favorite are 4-5 inch mullet, small pigfish or croakers no bigger than three inches and mojara. Larger baits tend to eliminate most of the fish ranging under about 18 inches on average. Fishing big baits means shortening your leader to no more than 8 inches. These baits are stronger and faster then smaller offerings like tiny finger mullet or mud minnows and are therefore harder for the fish to catch. By keeping them on a shorter leash, you keep them in the strike zone and in doing so, encourage more bites.