Accidentally put my grow light in wrong cycle. Two plants already starting to flower, what do?

I've planted a couple of seeds this year, started them inside, however, I put the timer in the wrong cycle, I forgot i had already programmed a 12 hour in there for other types of plants when I'm not using this light to grow canabis. I've just switched it back to the 18 hour cycle now chopped the heads off (i am super cropping). Out of 8 plants i am growing, only two started to flower, both are the same "amnesia lemon FAST" variety. Any way to save them or did i fuck them up already ? Cheers and happy growing season!