she is just having her first on she is 12 months next month how often with she have them after this

The seasons are usually 6 months apart, although that can vary between dogs.
My dobe had seasons every 7 months.
So the guide is expect the season around 6 months time but keep an eye on her fromn that time onwards because you can see the change around her back end when she is due to come into season, as the area swells. Hope this helps.

It can be different for each bitch, even litter sisters. I have Large Munsterlanders and one had seasons every 10 months to the day, whereas her litter sister was 6 months, almost to the day. A younger half sister never had regular seasons, the last 2 were only 17 weeks between, so I had her spayed. The bitch I have now has had 5 and 7 months between hers, as does her mother. 6 months is the expected time, but bitches haven't read the books ;-)