I would recommend you run your veg and flower period at night time for your plants in summer. This helps cut down on cooling and energy costs. Keep ventilation going constantly.

Under a 600w lamp, run them about 3-4 weeks in veg then flower That strain takes a while, about 12-14 weeks to finish.

You'll be fine with a few days of lag on the other clones, no biggie. If they are indica dominant, then you'll harvest those before the WW.