The lenghth of time can vary-- it really depends on when they reach estrus. This is when they ovulate. Some dogs ovulate as early as day 6 while others can be as late as day 16 or longer!
Once the bleeding slows down they are starting the estrus phase. I think normal from start to finish is 2.5 to 3 weeks. The first heat is usuallydifferent then the ones that follow due to horomones.
I cant believe our little angel is 8 months old already. Where does the time go???