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Personally, when I say soon it means that I may find time to look at it within the next two weeks.
If it is not a big change, I'll probably be working on it for 1-2 days.
However, it may also mean that it takes 3-4 weeks before I get a chance to look at it, plus some extra time to figure out how to do it, if the problem is bigger than I thought. Plus some debug time and testing that it doesn't suddenly create problems elsewhere in the code. That sort of thing.
So soon can be anything from 2 days to 1½ months. Really impossible to say - especially for spare-time projects.