Do you mean how long will it take them to merge work already done? That is, you have authored some changes and submitted a request to merge? Anywhere from a couple days to a week, in my experience. They're busy folks. If you mean "How long will it take for someone to listen to my suggestion and implement some feature I want for me out of the kindness of their heart." " The answer is roughly, "Whenever." It's a volunteer operation, really, so it depends on if someone has similar interest.
