Good info, ‘Aloha’...  Don’t know how authoritative I am on the subject, but I’ve done a lot of pruning   

If you summer prune, you’re often causing multiple ‘shoots’ to form instead of ‘one.’  I like that, because such ‘shoots’ often form fruiting wood or spurs.  Also, removing ‘water suckers’ allows energy to go into the stems or branches you’d rather have.

To me, ‘tip pinching,’ or removing the terminal bud helps guide a younger tree and keeps from wasting it’s energy on wood you’ll remove later.  But I never remove much wood from a tree as young as 3 during the summer - as I would from a tree 8 to 10 years in.  

With it’s energy underground while dormant, what’s removed with winter pruning is usually ‘replaced’ by spring growth.  Removing the bulk of unwanted growth from a young tree also eliminates it’s ability to store that energy come Fall … while removing larger amounts from a mature tree can help to lesson it’s viger and balance it’s growth.  

There’s a fine-line between the benefits of serious summer pruning of a young tree - compared to a mature tree.  If it were mine, I’d ‘tip pinch’ in order to create more fruiting wood (I think that works for peaches), to create a stouter frame (shorter branches), and to slow up (or stop) the unnecessary growth of sucker shoots.  Then let the tree collect and store it’s energy for winter, and do any follow up sucker or branch removal then -- or as another member has suggested - after it blooms, and prior to some dry weather