I don't mate the does again for a minimum of 8 weeks after their first litter is born. I usually leave the female babies in with the doe all this time, although if for any reason they had to be moved I'd leave them in for 5 weeks minimum. I separate bucks between 4 and 4 and a half weeks old from mother and siblings and I never have any trouble with them mating mum/sisters.
I think that's leaving the older does too long personally, as that makes them almost seven months old at the very least, and litter quality starts to decline with age. The rest period that is generally accepted as good practice has always been 3 weeks after weaning, which would make the babies 7 weeks old. I leave them for 8 weeks usually but that's personal preference not necessity. If you want show quality litters I wouldn't leave them that long tbh.
What happens if the doe has given birth but the babies have died or been still born, how long would you wait to rebreed. I'm tempted not to wait until 8 weeks as the doe hasn't had the strains of raising a litter.
I'd give it three weeks before remating in that case, just to let her build her reserves up again and get back to normal before the strain of carrying another litter. If she was still not 100% fit then maybe another week and then decide.