Heat cycles can start as early as 6 months to as late as 18 months
http://vetmedicine.about.com/od/pregnancybirthindogs/f/k9_estrus.htm
http://www.dogbreedinfo.com/breedingheat.htm

 

my girls came in around the 7-8 month , depends on the dog though. And the spay thing will keep males from producing lol but the humping thing may not stop my male will try and hum other males , even my females hump eachother lol its more a dominant thing then anything.

 

I have been told the humping is a dominant behavior. More than likely I will have the female done, as for the male, I have a tough decision to make. Only because I live in a house full of women and my pup and I are the only males here. Hahaha. But seriously, I didn't get my pups to be a byb. I too don't believe in them. I'll leave that to the pros. I got them cause I had one as I was growing up, my oldest daughter did as well and now since we've been blessed with a new addition she should too. Thank you both blue_nose_bella and angelbaby. PS those lniks were very helpful