She's going to get spayed
Keep in mind this is a kitten we got only 3 weeks ago, at which time she was estimated (by the vet) to only be 3 months old. I brought up the subject of getting her spayed up during her 1st vet visit 2 days after we got her. To the best of my recollection, the vet recommended bringing her in to get fixed when she's around 5 months old (they certainly didn't push trying to get her spayed sooner).
So to the best of our knowledge, this kitten has gone into heat for the 1st time at only 4 months old.
We already have a vet visit planned for this week to get her 2nd round of shots, so we already planned to discuss the subject of scheduling to get her fixed.
In the mean time, I was just trying to determine what else we needed to expect. I though I knew cats because we had a cat when I was growing up. That cat had something like 3 litters before my mom finally decided is was better to spend the money to get her fixed than try to find homes for another litter. But because she was an outdoor cat, I never saw this sort of behavior. So I'm finding that I know less about cats than I thought.