I am actually going to be going through something similar. I have a 6 month old spayed dutch and I am getting a male mini lop this weekend, he’s only 8 weeks old. I’ve done a lot of research and reading the forums on the bonding subject and in my opinion, you should keep them separate. Lots of people on here are constantly saying that you cannot truly bond two buns until they are both altered and recovered from surgery. Due to hormones and pheromones, these buns are likely to start fighting if you allow them to “hang out”. If a fight breaks out, they could learn to mistrust each other and this could make the bonding process even more difficult. Personally, I am keeping my 8 week old male in a separate room until he is neutered and recovered. During that time, I will do some pre bonding like swapping blankets and litter trays so that they get used to each others scent. You may be able to let them sit in cages beside each other, but it is likely that if he is unaltered and in close proximity of her that he will act up, which could ultimately upset both buns. I would try to keep them separate until after the procedure.