Just to settle a friendly arguement if a bitch started her season with a brown watery discharge would you class this as her first day or wait until it turns red any ideas?

Any discharge is day one, even if you only notice it on a tissue held against her. Not that it is very important because if you are wanting to know when she ovulates the day she started does not help very much.

I would say day one is from the first colour red/brown.  Ovulation as Jackie H says is a completely different story, as I have just found out, my girl ovulated on day 20!!