Introducing a kitten to our older cat: week one

We brought home a ten-week-old kitten last Sunday. Our resident cat, Pasha, is nine and not impressed.

So far the kitten has her own room, we swap blankets between them every day, and they eat on opposite sides of a closed door. Yesterday we tried a baby gate for five minutes and there was only one hiss.

Any tips for the next step? How did you know it was time to let them share a room?