Hi Rosie,
Bitches are like women .. no 2 are the same
As a result not all bitches will come into season once every 6 months. With some its 4 months, some could be 12 months and some could even be as late as 13/14 months between their seasons.
Unfortunately until she has had a couple it will be impossible to know exactly what her "pattern" will be. However it is my understanding that some bitches may not even fall into a regular pattern, they may be a couple of months out each time.
I also think that colour may have a slight influence on the regularity of seasons - for example parti-clours, such as blue roans, tend to "start" their season's later in life (around or after 1 year) and tend to have longer between each one.
HTH
Kel