Yes, I top at about the 4th through 6th node too and the ones in the pics above should have been topped long ago. Topping them now (assuming you're ready to begin flowering in the near future) will greatly reduce your bud harvest as the plant needs at least a month to recover from the removal. If done early in life they will double to triple in yield but if done late, shortly before harvest it will have the opposite effect. If those were in my garden I'd let them go as they are.