Regarding bonding, it’s always recommended that both rabbits be spayed or neutered before bonding is attempted. Has Juniper’s spay surgery already been rescheduled? Hopefully, that can be done fairly soon. My female rabbits never took a month or more to heal. They recuperated within 2 weeks (or less), and I was able to start bonding then. Of course, not all rabbits bounce back as quickly from surgery as others, but waiting a month or more seems excessive to me. My females started eating right away and showed no signs of pain after 2 or 3 days. After that, you never would have known they had just had surgery. I do know that other rabbits have had a harder time and will recuperate more slowly, but you can be the judge of Juniper’s recovery by observing her.
Definitely make sure that the new bunny has been neutered, and get a written statement regarding that. One other question you could ask is what kind of litter he is used to, and also ask your friend for his pellets and litter so that you can start mixing those with the brands that you buy for Juniper.