The honest answer is that only one part of it is genuinely open-ended. Everything after your offer is accepted runs on dates you negotiated yourself.
People ask how long buying takes as though the market decides. It mostly does not. Two of the four clocks are dates you chose, and a third is how disciplined your search is.
In practice the delays we see are the same handful every year:
Be ready before you look. View in batches so you are comparing rather than remembering. Tell your REALTOR® honestly what you disliked about each home — that is the feedback that sharpens the search. And decide in advance what you would say yes to, because the buyers who take longest are usually the ones who have never defined the finish line.