
Timeframe is difficult I would suggest keeping it flexibele but at leats at the end of the working day.
1st time is to discuss with the team explain the format.
Format:
Goal.
I might miss important goals but want to open the discussion.
A friend of my spend 2 years of wfh and introduced this within his team and after experimenting convinced the other scrum teams and it was a great success.
These are my 2 cents. It might not be worked out properly. But i think you get the idea.

It can be a nice optional pattern completementary to Scrum.
As Scrum does not limit teams for organizing a ‘virtual’ or ‘hybrid’ checkout, I don’t think there is a need to define one in the framework or Scrum Guide.
“As Scrum is being used, patterns, processes, and insights that fit the Scrum framework as described in this document, may be found, applied and devised. Their description is beyond the purpose of the Scrum Guide because they are context sensitive and differ widely between Scrum uses. Such tactics for using within the Scrum framework vary widely and are described elsewhere.