I have taken multiple flights to Florida on Jetblue around that departure time. For an 8 a.m. departure, I get there around 6:30. I have pre-check and always have plenty of time to get a snack. You can check security wait times by going to
www.jfkairport.com and click on "Security Wait Times" If you are worried about it being a flight to the Caribbean, you can get there a little earlier for your own piece of mind.