The lights will come on automatically once it starts to get dark, if you enter your PIN code at the front gate.  Lights stay on for 15 minutes after each booking.

If the lights are on when you arrive, that will be from the previous booking.  Always enter your PIN code when you arrive, otherwise the lights will turn off part-way through your booking. 

Once the lights go off, you can still enter your PIN code during your booking to re-start them, but it takes about 20 minutes for them to warm up again.