I don't know how many cows you run but if you sync them when you AI, then turn them out with the bull you should have a calving window of a month to 60 days at the most.
I would at least do it with the cows you are trying to get replacements out of. If you really want replacements look into sexed semen to use on those cows.
Not many cows, under 20 to breed. I did used timed AI for the past couple of years and actually had a pretty good ratio of those bred. But I didn't want a bull full time for just clean up so I leased and that went pretty well too, except I was always at the mercy of when I could get a bull in with them. Hence the spread out calving season.
As far as your bull I would have to agree, I do not like his topline or his heart girth, he lacks balance (looks a piecy, all the parts do not come together smoothly) For terminals use him and see what you get, if you like them keep him, if you don't sell him and find a new bull.
If the bull market is good this fall I may just offload him then with the others I am sending off.