Here in Northern Utah the earliest I've seen was New Years day. I saw this particular bull the day before(still packin) and went back the next day and saw him with just one side, decided to not push him since he was still on that ridge. Came back the next day and he was gone so went up and found the palm. It had a big ol chunk of skull/bone still attached to the base. I found the other side few years later on the same area but it was in some chaparel so it was tough finding in years past.
Most generally the bulls around here lose from first of Jan(bigger bulls) to the end of Jan first of Feb even (smaller ones).
I'd post a pic but it looks like they changed how you post pics???
Steve