sorry Tracey i would have to say you should move one of the dogs on unless ur going to get them seen to by a vet.
the bitch will be in season for approx 3 weeks but will only be ready to mate for 48hrs when is anyones guess(but the dog will know)
can you ensure they will be well apart (he is still young yet)but dogs have been known to destroy kennels,doors, etc when kept next to a bitch on heat.
And she will start to tease him when she is almost ready
as jan said bitch should be a least 2 or 3rd season(this is minimum)