First grow confusion

So I'm doing my first grow here. Have white rhinos from seed in pots from 3 gallon to 10. I have half on miracle grow (I know, first grow and experimenting) and half on fox farms and a steady consistent feed schedule. My question is I'm in northern Ontario, so grow season is short. Some of the plants have gone into flower. Some have flowered, then came back into veg and I'm attributing that to the fact we're still almost a month before Its dark out for 12 hours, which is when I'm told buds really start going. I'm wondering how to keep them in flower. I'm not really set up to time the covering so they're getting 12/12 until nature does it itself. Any thoughts on how to do that, please and thank you, would be great. I can only assume yield and quality would be much better if they didn't bounce back and forth...
P.s both feeds were switched to "bloom" feed last 2 feedings. Cheers