I typically prune them/train them heavy on the same day that I plant them (About May 1). Next training/pruning would be late August/early September - I will remove maybe 2-5 more branches. The next Spring I will remove more. I have done this successful for many years without issue. Other than the very first pruning on the day the tree is planted I try not to remove more than 25% of the branches at any one time.
Here is an example. I planted these 5 Red Wealthy's around May 1st of 2017. This photo was taken a little over 3 years later in September of 2020. There are no branches within 4-5 feet of the ground and most all of the other lateral scaffolds have been removed. These trees are pretty much trained into what I want them to look like when they mature. Only light pruning will be needed in the future. I know I shouldn't have allowed all of those apples to grow on these young trees - My Bad. I probably had already removed about 50 apples per tree from them that summer.
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