HELP!! 160w CFL and 600w dual spectrum...

Hi guys

This is my 1st grow. Im currently using 1x 60w cfl for my seedlings. They have grown pretty well in my ten. I was wondering when will it be a good time to start using my 600w hps. My temp average is about 78f and 50-55 humidity. Things are going well, i was thinking of leaving the 160cfl for another week and then putt the 600w on but far from my plants. Its been about 3 weeks since iv germinated them from seed (wet papertowel method) and they have grown well i guess. Green and healthy.