No DMs on the Ronkonkoma branch. Your best bet is driving up to the PJ line and getting that. The only one before it at 7:20. Last stop is Greenlawn, then non-stop to Jamaica.
There's one on the Montauk though that gets into NYP at 8:23. Starts in Speonk, all stops to Babylon, non-stop to Jamaica, then Kew Gardens, and NYP.