I have a 8:30pm flight out of JFK on a Friday. Traffic will be a mess, and I'd rather save the $45.

I'm thinking the best option is subway --> penn station --> LIRR train to Jamaica --> AirTrain to JFK.

Sound reasonable? Any other options I should consider? Think I'd be OK if I left at 6pm? I'm budgeting about an hour to hour and fifteen for the transit, getting me to JFK somewhere between 7 and 7:15.