Ok, so I honestly have no clue how old they are, I've just been doing this as a sort of "watch where the weed comes from" sort of experience. I have 8 plants, all germinated at the same time and all are at different stages lol So my biggest I wanna say is a bit over a foot tall (just did its first topping), and thats the only one that looks like its anywhere near starting a 12/12. Should I just keep it on a 24/7 until some of the others start to look like they're getting about a foot tall, or cut him from the herd and start a 12/12 with just that one? If you want pics for examples of when I say they're all different sizes and that only ONE is doing good, then just ask. I'm too lazy to go take pics that I'm not sure if anyone wants to see in the first place.
High there if it was me I'd wait for the other girls to catch up. She could use a week or two to recover from topping. Good luck
This isn't a bad idea considering the fact that you JUST "Topped" your biggest plant! I can't IMAGINE topping a plant, then IMMEDIATELY throwing it into flower! You top a plant in order to create more budding places. BUT, consider your space! Your plants will grow 2 to 3 times their size during flowering! Let us know what you decide and update us on your experiences! Good Luck!