When to prune white birch (betula papyrifera)?

Hi all! I’m maintaining a young white birch forest in my grandparents backyard. I’m puzzled on the proper time them to prune them. I’m seeing mixed reviews. ChatGPT says to prune during dormancy period (mid-October to late-April). Plants.usda.gov says not to prune white birch or other birches until summer because they are “bleeders” and should not be cut when the sap is flowing. Now, I did see sap oozing out this ‘older’ birch I cut down after a day or two back in April 20. I hope that’s helpful. Thanks again.