Time to top?

Its been about 3 weeks and she is 7" tall and growing everyday it seems. Im a first timer at this, so have never topped, femmed or trimmed. Ive been told to wait until more leaf sets form...could someone tell me if I can top her yet and maybe lead me in the right direction on how?

Thanks everyone...here is the pic (Blue Hash Plant)

You could top it now if you want. Just cut off the top set of leaves (use clean shape blade or scissors).

She's definetly ready to be beheaded!

Thanks guys...also, I have an identical plant whicim gonna mother....when can i start taking clones?

Thanks