Aight so what do you suggest put him with the heifers this fall or next spring. The 15 animals I bought the past 2 days very close to age, size and body condiction. I would say the youngest is 5 months and the oldest 9 months. I can really throw the feed to them to build them up.
That really depends on when you want them to calve, personally I would rather calf just ahead of the spring flush so that would suggest a late spring early summer breeding season, but I am sitting about 15000 miles away in a very different environment.
Trying to breed the 5 month old heifers this fall would be pushing your luck, so I'd rather wait till next spring if feasible at all and join them all at the same time. Or you could join them in the winter for fall calves, but that would bring a whole lot more management issues and increase the cost of getting them through the next winter while suckling their first calves. Like I said buy a weight tape to give you an indication of size, 800lbs and 14 months is usually a pretty safe bet.