I find different strains start faster then others after you switch them to 12/12.
You have a nice, longer then normal, veg on your plant, what kind of lights and pot sizes did you use for vegging?
The topping could of easily set them back a few days, so you should start seeing pre-flowers any day now. With the topping it should have also came with the benefit of bringing the side branches closer to the top, creating a more even canopy for bud sites. If you topped solely for just having more tops, I would of suggested against it and topped for more tops earlier in veg.
That small LED will do nothing to the plants, so you don't have to worry about that. I know I have heard of frequent driving at night by greenhouses with effect the plants recieving that light, but I run small lights and my TV when the lights are off and I know a little light has to get in there, because light comes out when the flower lights are on, but it doesn't effect the plants at all.
You seem to be doing well without pictures to tell exactly. Keep going on you should have some good puff!