
It's like women, in fact the average for bitches is more like 7 months I read somewhere, but anything from 4 months to a year is normal.
Many of mine have had more frequent seasons at first, (4 - 5 months) and then seem to settle to around 6 1/2 - 7 months, but my two half sisters most recently one has gone 8 months the last few times the other has done 7, then 6, then 7 1/2 after puppies and then 8!
So the only thing I can say trying to enter shows is a nightmare and I have missed shows by not entering expecting a season, and they haven't come in, and then entered them and had to waste my money when they did.
It certainly does seem to be breed/line dependent to a large extent, and 10 month gaps was usual for my friends Welsh Springers.