Second year cherry summer maintenance questions

Hi everyone, so this is my second year of growth for a multi-graft cherry. I’m trying to keep it <=6’ but already I can see what kind of pruning battle this is going to be; some of the branches have already put on 3’+ of growth this year! I’ve watched a few summer pruning videos and still have a couple questions…should I be removing crossing branches now as I see them? What about removing new growth that’s oriented underneath the current scaffold branches?

Here are a few pictures…

You can kind of see a few laterals (all about 12" long) growing left and right off this main scaffold, should I leave them or prune them to open up the tree for better airflow?

The upper branch of the one I want to keep, so should I prune the lower growth now or wait till it’s dormant? (Both new branches are about 24" long already)

Thanks for all the help, this is all new to me so I’m kinda learning as I go…