Originally Posted by
Analise
First, it would be the subway plus bus. No subways go to/from LGA. Second, subways in the middle of the night don't run as often (neither do the buses) so you can look up the schedule for the specific subway and bus schedule online to see if this would work. Doubtful.
It's totally doable by public transportation, though you do need to leave extra time for reduced overnight service.
Here's the Q70 bus schedule. It would be easy to figure out which LIRR trains to Woodside connect to the bus, or one obviously could take the E, F or R to Jackson Heights/Roosevelt Avenue (the M does not operate overnight), or the 7 to either Woodside or 74th St./Broadway. That said, while I would be very comfortable leaving midtown at 4:30am for a 6am flight if going by taxi or uber, if going by public transportation I would want to leave an hour earlier, so I'm not sure if it's worth it.