While it may suck to hear you need to wait, you do need to wait. The ideal candidates for rabbit bonding (ideal, because there’s no guarantee any two rabbits will get along as lifelong buddies) are two fixed (i.e., spay and neutered) rabbits. There is no way to predict when hormones may arise in young rabbits and the “bond” between a pair of rabbits where at least one is not fixed is extremely unstable and dangerous to leave alone. It only takes a couple seconds for a rabbit to be impregnated, as well as seriously injured– they work fast.

You need to wait several months until your rabbit is spayed and fully recovered before considering getting a possible bonding candidate, and while I know you want a young rabbit, both need to be fixed. If for any reason you get a second rabbit and either are not fixed yet, they need to be kept completely separate with no interactions to ensure their safety.

Of note, time and time again it is shown that having a rabbit since they were young versus when they are an adult doesn’t really impact their trust or social habits, if that is why you are attracted towards getting a rabbit of a young age. I’ve volunteered at multiple rabbit rescues and have worked with many, many, many rabbits, and it’s very much the individual rabbit and the owner’s ability to provide a good environment + be able to read rabbit body language that directs how friendly a rabbit may be. One of my cuddliest rabbits is one I adopted when she was 8 years old and (as most rabbits in rescues) was not taken care of well prior to me getting her.

Parroting what Wick&Fable said, yes you need to wait until she is older enough to be spayed (4-6 months, depending on the vet you use and her breed) and her hormones have settled (usually 3-4 weeks post-spay, but sometimes longer).

Best chances of success are with a neutered male, so if you can find a rescue you can adopt a neutered male, or even take her on speed dates to find a good match. I would not recommend a female, this is usually the hardest combo. Also you may find that your female ends up being male, because baby rabbits are very often mis-sexed, so another good reason to wait!

Also just to comment on your point that you wanted to get babies, I encourage you to think a bit more about this. Babies are only babies for a short while, and it will be much easier for you (cheaper… and less waiting time) if you can adopt an already neutered male once you are ready to start the bonding process. During the time before they are bonded they will need to be housed separately, and hormonal rabbits are honestly a lot of trouble. They are very smelly and have terrible litter box habits lol. As much as babies are cute, there are so many adult buns that need homes and you would have a much better chance of bonding success if you could bring your bun on some dates to select a good match.

It is totally fine to bond different ages! I’ve had seniors bonded with 2-3 year old buns and they got along great.  Size of the buns also doesn’t matter. It really doesn’t matter at all as long as both rabbits are healthy and castrated. Same sex pairs are possible but tend to be much more difficult, so usually it’s best to go for an opposite sex pairing.

I echo Dana’s sentiment — do not follow pet store recommendations. Employees may be friendly, but their knowledge about rabbit care and their standards are typically much different. Many pet stores employees are told general things about care, like rabbits do better in pairs, but don’t know the important details, like the need for them to be fixed and bonding can take weeks or months.

I would wait a while, it’s good you want to make sure Lilly has the best life possible, but you don’t have to rush to get her a companion right away. Maybe by the time Lilly is old enough and well recovered from her spay you can reapply for that adoption application and show you have much more experience with rabbits! You won’t have to buy another baby one then and go through the possibility of getting a misgendered bunny. In the meanwhile you can invest time in researching the bonding process and what you might need to carry it out successfully. As Wick and Dana said, pet store employees REALLY aren’t credible when it comes to rabbit knowledge, if there’s specific things you want to learn more about it’s usually best to look on the forums or House Rabbit Society, or ask a rabbit doctor.