When I (a woman) needs to go to JFK, I take the E train to Jamaica The train runs express a fair amount of the way, and the "rush hour" will be running the opposite way, and it will be less than normal due to the holiday. Then take the airtrain to JFK. I "timed" it from Chelsea the last time, and I was at security about 1 hour after I got in the train. Cost = $7 on your metrocard

I would not take the A train all the way to Howard Beach as it takes MUCH longer than the E train.

If you are in the E train by 6:45 or 7:00 (with boarding pass in hand) you'll get their in plenty of time.

Good luck.