Jo -
IMO there is no down time with a BAHA implant, but then again everyone is different.
I've never heard of anyone staying overnight for BAHA surgery, but then again all docs are different.
Usually BAHA implants are done outpatient - and a lot of them are done with local anesthesia; mine was. It's a short procedure about 90 minutes and recovery is swift.
I had a little bit of pain post op in the afternoon (my surgery was in the morning) and a little pain the next day. Extra-strength Tylenol did the trick. I went to lunch after the procedure and then to my son's volleyball game - sporting my nice, new "BAHA hat" - which thoroughly embarrassed my son (hey, what are parents for?)
I took the following day off of work because I was still wearing my hat (had to keep it on for 24 hours) and I thought my colleagues might consider it "freakish".
Jan