personally I wouldnt top now, but like Bone said if u r gonna do it, than do it now. and plant that top too if u r gonna do it. should root pretty fast and can prob get into flowering in 4-5 weeks. other than that, the best advice is to keep using ur grow nutes into the 3rd week if u r using the correct amounts, i.e. no burn. slowly work in your bloom nutes and gradually ween out the veg as you go from week 3-6. that will prevent you from making the #1 newb mistake of cutting veg nutes too early (N) and getting premature yellowing that will effect your final yield. and rotate your plants every other day.