Interview- when to enquire

[Lushmetender]

Went for an interview. Was told by HR I was their favourite so far but still needed to give others their second interview. Contacted them with completed expenses form and hr wanted to give me an update. The interviewer had had last minute travel and now they were delayed. That hR had to move things around and would provide feedback ASAP. That was about 10 days ago with no update recently. Originally they said theyd hoped to provide an offer to someone early dec. I know that timeline hasn’t passed yet but when do you think it’s realistic for them to get back? Should I enquire re their new timeline?