People seem to put dairy cattle in calf to calve for the first time at 2 years old, but with beef cattle, especially the native breeds, it's more normal to give them another 6 to 9 months. For some native breeds you wouldn't want them to calve until they're 3.
So if it were me I would be planning to inseminate her on turnout next year, when she's just short of 2 years old, for a calf at around 30-33 months.
As they sometimes don't hold the first time, and sometimes don't hold if they are inseminated at the same time as a major change in routine, maybe have her served a month before turnout, so you've time to catch her again if she doesn't hold the first time, and her routine isn't changed immediately after insemination.
As to choosing a bull; for the first time you want short gestation, easy calving, calves that jump up and suckle quickly - and frankly not worry too much about getting the perfect calf. Plenty of time to get better calves later, when she knows her job and all the passages are loosened up!