I don't really have any input about the breeding aspect and the potential age difference, but I'm sure someone with breeding experience will be able to offer some advice there.
Honestly, I would always encourage people to choose rescue over buying a newborn hedgie if possible. Rescuing a hedgie can have some drawbacks, though. Depending on what sort of environment the hedgehog is coming from, there can be behavioral challenges. Some people find that their rescued hedgehog is quick to warm up, but this is probably the minority. My hedgie Felix is a rescue whose previous owner wasn't taking very good care of him and hadn't bothered to spend any time socializing and playing with him. I've had him for around 2 months and he is still incredibly jumpy/nervous (will ball up due to noises, sudden movement, or sometimes for no reason at all) and usually will not allow me to touch him very much when I have him out of his cage. Breeding perspective aside, this is definitely something to consider from an owner's perspective since your new little girl will be a pet and a part of your family as well as a hedgie mommy.
If you're comfortable taking the risk that you may end up with a slow to warm up hedgie and you don't mind taking the time to work through it with her if this is the case, you should go with the rescue in my opinion.
But you definitely shouldn't feel pressured to do so in any way. Go with your gut and choose whichever seems right for your situation.