For the best answers, search on this site https://shorturl.im/axeM9. Usually dogs come into their first heat at 6-9 months of age and approximately every 6 months from there. however it is better for your dog to wait to breed her untl after her 3 or 4 heat. it gives your dog a to mature kinda like the difference between a 16 yr old having a baby and a 20 yr old.