Hi Lazybones,
I haven't much to add to Megaloo's reply, apart from to say you may also notice that your bitches recall becomes poor about a month or too before she comes into season. My experiences include 4 bitches, three GDBA bitches who all waited until a few days before they were a year old to come into season for the first time and now my own Lab who is currently in season at 9 months.
I'll think you'll know when Ruby is planning something, but it's worth remembering it usually happens sometime like just before you go on holiday or just when you've had that new beige carpet laid or, like one of our bitches on Christmas Day! :lol:
Clare