We had this "problem" here at Coble Highland Ranch, also. We bought a herd of 7 Highlands (6 heifers and 1 bull). I have always been raised around Angus and other cattle and thought for sure these heifers (the youngest being a yearling) should be of breeding age. Needless to say, I took them to the vet for preg checks after several months of having them. We sold the bull after finding out that none were pregnant. (9 months later, however, we have one of his calves on the ground. That's a different story, though). The youngest, who is a little over two, just came into heat and we witnessed her breeding. Lilly (who was born October 2007) just got bred this past month. From what we have researched, Highlands are just slow maturing. So, bottom line, I would think they they have a little longer to go before their first heat. I hope this helps and if you have any other questions, feel free to ask!