I don't think you'd have to wait 2-4 weeks. I would try going the "exchange scent" thing (trading toys) and let them get used to that in the next few days, then open the bedroom door and see how it goes. If it goes bad, separate them again and try later. I found Tito and Sophie were very nervous around each other for a couple of days. There was a lot of chasing each other around the house at top speed. And don't be surprised if little Brodie does the "kitten hiss" (which is so cute, by the way, when they hiss) - he's going to feel threatened by a bigger cat. Sophie hissed at Tito a lot too, and even growled a little. But they both got over it and were fine within three days. Hopefully you have as much luck as I did.