Should I start Topping or is it too early?

Nope, you're good to top. The rule of thumb seems to be to top the plant in between the 3rd and 5th nodes. No sooner, no later. I hope this helps.

It would depend on the strain. If its a strong plant, which it looks like it, could top now. I top my plants as early as day 18 from sprout.

How bushy do you want it? What type of training if any are you planning on using..these factors and more weigh in on the final decision...in general node 5 (unless a serious manifold grower) is a good place to start so you have about a week left before topping imo,..if thats what you chose to do. Hope that a helps. Sticky Buds!