In Australia rabbits are vaccinated against RHD. I believe the babies have a natural immunity while they are still nursing, however I'm not sure if that is affected at all if the mother hasn't already been vaccinated and built up her immunity. I'm finding different info on the age range to first give it, from 4-12 weeks, with a booster a month after the first vac and revaccinated after 6-12 months. Best thing to do would be to phone up your rabbit vet and get the info from them. I'm guessing they would need to get vaccinated around weaning time, and the mother as well.
http://rabbitvet.net/AustralianRabbitVets.htm
https://www.therabbitdoctors.com.au/vaccinations