When your husband asks "Can we go now?" or "When can we go?" I am afraid you will just have to answer, "No, dear, we cannot go yet. You have to stay here for some time yet."
But does he mean, when can you go home together, or simply when can he go back to his own room?
Talking about something else - something or someone he remembers might work, or might nok.
Try telling him things, like I spoke to the neighbours today about such-and-such, or tell him something that actually has happened,
When my sister was dying of brain cancer which had destroyed her short-term memory, she became very upset when I had to leave, asking how she was to get home, and where her coat was.
She was in a hospice and I knew very well she would never go home. I replied, " I have to go now, M, I'll ask the nurse to come in, she knows where your coat is, and Mummy will be along to fetch you soon." (Mummy was 17 years dead by then, but it worked, consoling my sister.)
It is horribly hard, and you probably hate yourself for lying, but look at it this way - you are not lying, you are trying to join your husband in his world and doing as well as you can, as you have neither road map nor compass.