I just found this reference from the ASK TSA Twitter Page.
http://onemileatatime.boardingarea.c...sa-wait-times/
TSA Precheck at JFK T8 is generally open 5 am-8 am & 1 pm-8 pm. Hours may vary based on the passenger volume.
According to AirfareWatchdog's TSAPre Hours Chart
tsa_precheck_chart_feb_2014_update_chart.pdf
T5's PreCheck Hours are only:
Terminal 5, Main Checkpoint: 6:00 AM–9:00 AM
Terminal 8, Main Checkpoint: 3:30 AM–10:00 PM