I have not tried any holidaying on FM23, but in recent versions, the slowdown from the initial speed is very fast. I used to think that I or somebody else would easily break my record by now, but that has proven to be rather difficult.
Also, with lots of leagues loaded, one bug in one of them can derail the entire file. Unless you are trying to get ahead of other people for content creation, I would wait until at least the official release to start a long-term holiday save.