Once a bitch has had puppies do they give off a stronger scent than when they were virgins?  The reason I ask is my boys go mad now from day one when Tigs is in season and yet before nothing used to happen until day 10

was it your boys first mating with her on her first season because if it was he now knows exactly what that smell means and is more confident in himself so he will start bugging her more earlier

No it wasnt.  My younger boy has never been used but my older one who has has been going mental since she came in season yesterday.  Tom is usually very laid back until he knows the day is right but he is going mad.