If she starts going sideways, just stop with the nutrients. Most grow soils (and I have no idea what you are using) have beneficial nutrients enough for seedlings. Just wanted to share my 2 cents, good luck with your grow!
I'm growing humbolt GC too. I can give a few heads up. She likes as much soil as possible. The branches get big, but quite hollow. This can be an issue when training. I had a branch split while screening.