Don't bother pinching and trimming a runt. Only cut the tops if it looks like a plant is going to get taller than the grow space allows. I don't where concausions gets the idea that pinching and trimming is to deal with stretching. This person is putting out some bad ideas. Why experience is required with CFL bulbs at 5 inches or less is a bizarre thing to say. It's heat from the bulb that you're primarily concerned with. If you have any source of light very close to a plant, there are two things that happen - one is heat damage (but CFLs don't put out much heat), and the other is growth response, i.e., a plant will grow very short and bushy when a strong source of light is very close. I'm primarily talking about MH and HPS here. Close CFLs should be fine as mentioned by pushit. Keep lights close and see what happens. Flouro light isn't a strong source and they run cool, and I don't think there's much to worry about. As they grow, back the lights off some. It looks like some stem stretching has taken place already. Don't trim anything, just let them grow.