Don'tcha hate it when these things happen?
It sounds broken (but little bones are flexible, so it's always possible it's not, and is just soft tissue damage... but it certainly sounds that way).
That said, what they'll do depends on where and how it's broken. If it's the interior bones, or exterior ones... whether or not the bone is misaligned & how... whether or not there's cartilage damage. If there's any setting that needs to be done, mine has always been quick... "grind, snick!" Or "snick, snick, fwoosh" (the fwoosh sound is the blood rushing to my ears).
The thing about a broken nose (if it's offset), is that it hurts UNTIL it gets set. After that it just aches...but the pain difference is so great, that you almost feel pain free for the first few hours. It's like snick-ahhhhhhhh. I've had my nose set as long as 9 days later, without any rebreaking needing to occur, but that was as an adult. It's HARD for an offset bone heal... but given long enough it will. I don't know what the timeframe before restructuring begins is for children.
My niece, though, has broken her nose twice. Once at 1 year and once at 7. The first break they had to do exterior and interior work. They put off the interior work indefinitely. A "wait and see" approach (setting the interior bones involves essentially sticking a pen up the nostrils, and is usually unnecessary). The wait and see was if there would be any difficulty in breathing. None yet. If there ever is, she'll essentially get a free nose job, since it's documented repair work from an old injury...it'll be covered by insurance. She DOES snore now, but there's nothing aesthetically wrong or that causes difficulty breathing asleep or awake. She just snores. The second time she broke her nose (softball to the face in school)... one of the other kids reached out and tweaked it. Luckily, he tweaked it in a way that set it correctly (although she kicked him hard enough that the emt's took both kids to the hospital).