Ugh. I broke my collar bone when I was 10 or 11 flipping over a bike (got a concussion and a little memory loss to boot!)
I'm sure it depends on the break and some other things... I had a complete break and had to wear a brace and sling for about 3 or 4 weeks, and then a sling for another week or so. Of course, I was 10, so maybe that has something to do with healing times. I also went to physical therapy once a week to have the brace adjusted and go through awful exercises.
Online, people say 6 weeks is about average in adults.
It's been 15 years and the collar bone I broke is still positioned a little lower than the other one. The doctor had mentioned to my folks that this was a possibility. I don't think it limits my motion or anything. No clue if that happens to adults or not.
Good luck!
t