I would definitely try a different circuit. If you plug the light directly into a new socket on a different circuit (older wiring may not trip the breaker but might not provide quite enough power to start everything correctly).

One of my flowering rooms has 2 600 watt digitals. Ive had horrible issues with the breaker tripping or one of the lights not lighting up because of old wiring in the house. I eventually had to run an extension cord from a seperate circuit (one not connected to 2 700 watt gaming computers and a bunch of fans, etc) and I installed a 20 amp breaker instead of 15 (after inspecting the wiring) and Ive been chill ever since.

Sometimes there is enough power to get the light to sort of go on, but not enough to ignite. My old 250 watt HPS took about 5 minutes to fully start up, but only a minute to ignite. If its happening twice, then you should look at your timer/electrical situation.