i can tell you i have a cherry tree ive trained round an old swing and a weeping cherry over a seat and i have to trim both quit often as and when it needs it and there fine . the only trouble is you wont get many cherries next year if you trim it this year .i dont know about the other tree sorry . i also know that theres wayes to take bigger branches out to keep the tree airy and take branches of real close to wear they join onto the bigger plant if there big . also if branches are rubbing on each other you take them out . if your just doing the outside shape like a hedge if you will just do it when it suits you . you mite be able to pollard them but im not sure .