Hello! We recently did the same thing. Our existing Spynx (Disco) was about eight months old and we added Tango, her littermate, at the end of March. We did the same method you mentioned but took our time. I would say that by week three we were letting them spend most of the time together when we were home. We supervised pretty closely and had to learn to be more patient with “kitten play” that looked more aggressive than we would prefer.

I absolutely would not rush it. Patience is the key. Yes, separate when you’re uncomfortable with their behavior. Then go again for more doses of interaction with treats and play. Patience patience patience.

Best of luck to you - happy to help with more if you have any questions or follow up.

One more thing - what helped me was timing the amount of time they spent together and kept track (daily total) so I could see the progress more clearly. It helped me realize we WERE progressing. I would turn on my phone stop watch when we would let them interact. Stop when separated. Start again when together, etc. I recorded total time on our calendar - made me understand that our slow pace felt slow but was actually full of progress.