I topped one of my plants recently while she was in a solo cup and I had no problem, transplanted her like 2 or 3 days later. She was smaller than yours tho, your plants look ready to be transplanted. I ready on a couple of forums about transplanting and topping on the same day, I didn't do it but they said it was fine.
I don't think I helped you much xD, sorry I have very little experience. If those were my plants, I would transplant first and then top (a couple days later), since, in my mind, after you top the plant needs more space to grow her roots.