Sorry to hear bout the poor weather deal. Dont switch your lights to 12-12 till the other one is harvested. It will have a negative impact on your yield . Cold lose 10-15%. My suggestion is to leave everything as is for now. Like I said its likely just a different phenotype. My GSC are doing the same thing 2 of them were almost 4 weeks into flower before the other one started flower. Each strain have a " common " life cycle so essentially the company will advertise the most common life cycle. But some could take less time Nd others may go a month or over. My GSC are advertised as 65-75 day strains . I'm over 100 days now and 2 are just ready to be chopped this week. The other I would say has at least 3 weeks to go. So I assume your going through the same thing. I suggest you leave it. But I am also new to autos. It's like the army. No man left behind lol. I think you'll be very happy if you dont give up on her. What do ya have to lose. If when your other one is ready for harvest this one still isint flowering. Then you can switch to 12-12. And really all that means is you'll get a better harvest from it due to it's longer time in veg