My black lab six months old

Question
Please tell me, when is she going to have her first heat, she is going to be seven months in 08-13-2010
How we will known that she is close to.
Thanks,
Abigail

Answer
There is no way to know exactly.  It could happen any time now up until she is 24 months of age.  It all depends on her lines.  

The tell tale sign is that you will notice her vulva swelling a bit before she starts showing blood.  

Any reason you are waiting and not spaying her now?