I'm following a manifolding tutorial with Beatrix and when she reached her 5th node this week and was generally very healthy and vigorous it was time to top her. I topped her at the 3rd node, then removed everything below that node. I left the big fan leaves of the 3rd node to give her some extra power as the growth tips grow. As soon as they are big enough they'll get bent to a 90 degree angle.
She's not getting 20 hours of light and I have started her on the usual Fox Farm nutes.