Players who are injured heal a little bit each day, so a player might have 7.2 week injury or a 7.4 week injury, which will be displayed as a 7 week injury. I don't know how BB rounds, so possibly those will be shown as 8 week injuries.
A player of a particular age and a particular doctor skill might heal 0.2 weeks each daily update. So his injury time would reduce one week every 5 daily updates.
I had a 20 YO, and a level 6 doctor, whose injury time reduced 1 week, roughly every 5 days. Your player is 22, so he is a bit older than mine. But your doctor is slightly better than mine, so I would expect the healing rate to be about the same.
Since your player has 6 weeks of injury. I would expect it to take around 6 x 5 or 30 days for him to be healthy again. I don't know how much faster a level 9 doctor would be.