I guess you know why I say, "people who believe in the saying 'breed like rabbits' have never tried it!"
I prefer to quarantine a new rabbit for at least 2 weeks before trying to breed them. That gives them time to adjust to all the changes of their new environment, gives me a chance to get to know them, and provides some time for any disease/parasite problems to show themselves.
Rabbit does don't do obvious heat cycles, but they do experience hormonal fluctuations. Like most animals, the cycle they do is about 28 days. Rabbits are what are called "induced ovulators". That means that they ripen eggs in their ovaries, but don't release them until the act of mating triggers the release. Since an egg only remains viable for a short time after it is released, this greatly increases the window for becoming pregnant on a given cycle. When you want to breed a doe, flip her over, and check the color of the lining to her vulva. Gently pull her tail toward her spine, and press just in front of the vulva. That should cause a little of the lining to be exposed. If the color of the lining is pale pink, the doe is at a low spot in her cycle, and she most likely won't breed. The optimum color is a bright, cherry red, that signals the peak of her cycle. A doe that shows red will most likely breed readily, and will probably kindle a nice litter. If the color is purplish, she is past her peak, and may not breed. Even if she does, her eggs are aging, so she may or may not get pregnant.
Rabbits are somewhat responsive to day length. Some rabbits will breed in the dead of winter, others are more reluctant. You may need to extend their "day" with artificial light to get them "in the mood". A doe that is overweight won't be experiencing the deeper fluctuations that inspire them to breed, so it is important to limit the amount of feed a non-pregnant doe gets to just what is necessary to keep her in good weight. Some does show overt behaviors like digging in a corner, chinning objects in the cage, grunting, and fur pulling when they are near the peak of their cycle (digging and fur pulling also are signs that kindling is about to take place, so be sure you know that the doe isn't pregnant when you see that!). Some does will raise their hindquarters when you pet them - that's a sure sign that a doe wants to be bred! If a doe just doesn't seem to like the buck, sometimes putting her in a cage next to his for a while will get her past that.
Good luck!
(oh, btw, on the one that quit eating? look up "GI stasis")