You’ll need to keep them apart after about 12 weeks old as they can get quite territorial otherwise and potentially fight one another. You can’t put them back together until both have been neutered and spayed and their hormones have disipated. Also, a male can impregnate upto a month after he has been neutered.

At their age, it’s probably best to go ahead and house them separately. Since they will have to take turns coming out for exercise, they may not get quite as much as you would like, but hopefully it will be adequate for them. Don’t keep their caged adjacent to each other since rabbits have been known to get pregnant through cage bars and they can also bite noses and such through cage bars. As they get a little older, you may have to place an x-pen around a cage or somehow block off a cage when a rabbit is in it and the other one is out exercising, if you see any aggression starting through the cage bars.

They cannot be together until both have had their surgeries and a few weeks has elapsed. Then you can start proper bonding. You can do some pre-bonding by swapping blankets, toys or anything else that has their scent on it.

You aren’t ready for this yet, but here are 2 good articles on bonding:

https://binkybunny.com/BUNNYINFO/tabid/53/CategoryID/9/PID/940/Default.aspx

http://rabbit.org/faq-bonding-multiple-rabbits/

I have had a lot of success bonding rabbits by using an x-pen. My rabbits were spayed and neutered of course. My husband and I get in the x-pen with them to stop any fighting (some scuffling may be normal) or excessive humping. We start with a few minutes and increase the time each day.