I guess so, start of calving is May 1, Bull goes in about July 15 -  70-80 days max. But some cows will calve in early June (45 days after 1st  calf) and that would be only 30 days ahead of bull in date.

This points out the importance of sticking to my 2-cycles (45 day) calving window or they're gone.

This whole discussion assumes you have a good, what I call a "chaser" bull or bulls!