We saw one last July - really amazing. You are not allowed lights on the beach and they really discourage too much traffic on the beach at night.
I believe the nesting season in June - Sept. but someone else might correct me. Depends on the type of turtle as to when they nest.
If you hit the beach early in the morning you can sometimes see them digging up a nest and possibly get to see a couple hatchlings. They are GREAT about answering questions and encouraging you to learn and watch. We also go to see them dig up a nest and try to save two babies. Not sure how early we were out though?