If i could give you any advice on topping it would be to let the plant veg for at least a couple more weeks to let the growth get back to normal before flowering. When you "snip the tip" it will pretty much stall the growth of your plants, you want both your colas to develop some nodes before you flower so you end up with 2 quarter ouncers, instead of 2 1 grammers.
It seems like you have enough height in your closet to let them grow a little longer
I can tell you this as from experience. I grew too many little tiny colas before i realized topping earlier ( if at all, im still on the fence on whether topping your plants is worth the extra time for a small increase in yield, maybe this time is better spent healthly growing the plant?) is better idea. That way you grow two main shoots which will have shoots come off of them, and fatter colas. also that way they're much more stable than top heavy late splits.
In my humble opinion, i would say for a first time grower, dont worry about topping this round. Some plants are really finicky and just dont take well to trimming, it would be a shame to wreck your cherry grow if something were to go awry. If i were you i would veg them another month or so and put em into 12\12 without any butchery. Get this one under your belt and then once you're comfortable with the whole process of growing try all sorts of things until you find what works best for you. Of course its your choice, but i say keep it simple, at least until you have your feet a bit wetter.
I look forward to seeing this grow progress, just remember, theres lots of people on the internet (im one of them) who like to go around and spread their opinions as facts, take everything with a grain of salt and use common sense, and be patient. The ganja gods will reward you.
Good luck and happy growing!!!