Only really use the flouros for about 10 days max. I'd be inclined towards a week but it all depends on the strain. Then put the hps on for for the next few weeks. Start with the light at about twelve inches above the tops of the plants. When you put on the big light rem' to give your plants a nice feed, so let them dry out a little beforehand. Give 'em something special too like some nutes. if you can, organise a way to move the flouro's around to the sides of the plants. You'll need to keep the plants on 18/6 for a few weeks. Or until they are from 12-18 inches tall. Then switch the lights to 12/12. You only switch to 12 12 when plants are big enough to flower.