The Doe has no regular cycle of coming into heat and she can ovulate at any time of the year in response to the advances of a buck - this is particularly true in the summer when the environmental factors are favourable.
The Doe can become pregnant perhaps ten times in one year and this makes it impossible to allow the buck to live with her.
This is my personal experience of breeding rabbits which I did for over 8 years. It may differ to the information you find in any book on rabbits but it has worked successfully for me!
I do not leave a male and female together in the same cage for longer than a few hours. I feel that its unfair on the female to remove her from her own surroundings for much longer than this. One thing to note is that you should always put the female in the males cage and not vice verse she will probably attack him whereas he doesnt seem to mind (well he wouldnt would he?).
I prefer to let both the male and female run around the garden together and if they want to breed then they will! It is usually the female that may not want to breed so if she appears unresponsive leave them until a later date dont force things. If you want to (more or less) ensure that the Doe is pregnant you will need to watch them breed dont worry you will almost certainly known when the deed has been done! I admit that I do watch them breed so that I can help plan the pregnancy for the Doe. This entails feeding the Doe twice as much, providing her with extra hay and nesting material, and trying not to handle her too much would you like being picked up when you were pregnant?
Although Does are usually able to conceive at just three months of age it is not recommended. Ideally the Doe should be about 6 months old.
There has always been the problem of too much inter-breeding whereby males and females from the same, or closely related, family are continually bred. I have bred (accidentally) brother and sister and fortunately the litter were fine. You will hear people saying that inter-breeding causes deformities and the young are born minus legs and with two heads etc. This may be true, although I have never seen it, but more realistically you will find that the young are much weaker and may not live as long.