You have to be really careful with breeding as it can easily get out of control, plus if you breed your buns too young it put's their health at risk and you could end up losing the mum. I'd wait till the doe is at least 6 months old, preferably closer to the one year mark.
What will you do with the babies? Keep them or sell them/give them away? If you're not planning on keeping the babies then will you be able to find good homes for them in advance. It's just there are a lot of unwanted bunnies out there, you don't want to add to that number. Plus anyone who takes one of the babies could have rescued a rabbit from a shelter instead.
Are your bunnies proven thoroughbreds? I can understand breeding to contribute to a specific breed if your bunnies are excellent breed standards, or to keep your bunny family going (ie. keeping all the babies or the vast majority). But please don't breed because it sounds fun/interesting, or worst of all to make a profit.
I'd wait and make sure you can handle the 4 bunnies as it is, wait till the does are around the 1 year mark before breeding. Make sure you have room and the funds to support 24 plus rabbits (2 litters of 10 from each pair is quite possible). And make sure you do lots of research before hand if you do decide to breed, it's not a walk in the park especially if the mother rejects the kits or you end up with still borns, runts, litters too large for mum to handle and canabalism. Good luck.
And welcome to the forums, I'm a newbie too! :wave: