I can give you an idea of what worked well for us. We had Pumpkin for about 5 months before bringing Shamrock home. We knew they would be living together in Pumpkin’s current condo in the living room eventually. I wasn’t comfortable housing them next to each other in the living room b/c it was quite obviously Pumpkins territory and I knew she would freak. So Shamrock spent a couple weeks in our bedroom and then we switched their living spaces. It gave Shamrock a chance to get his scent all over everything in the living room and made it less of Pumpkin’s territory. We did this for a week and then started bonding sessions in a completely neutral territory (bathtub).
After our longest bonding session (11 hours in a pen in the living room) we starting letting them sleep in side by side pens (one in the condo and one in the pen in the living room).
Then deep cleaned the condo, washed the blankets, and cleaned the rug. We put in a brand new litter box and let them be in the living room and condo together (supervised). We are ALMOST there.
Sorry for the long post, but I thought what we did in the beginning might be helpful.
I personally would wait until your new little gal is spayed and healed before I would start introducing. Hormones are gonna be wild
Good luck!!