The ideal is to meet up after every lesson, in the mentor’s home with just the two couples. However, you can also meet less frequently covering two to three lessons at once if time is scarce.
You can also meet in a different location such as at the parish or in a café.
For couples who live remotely or are travelling, these meetings can also be done over Skype, Facetime or What’sApp or other VOIP service if necessary.
And some parishes prefer to meet in groups with several engaged couples at once, perhaps with the priest also in attendance.
The point is, the meetings are completely flexible in terms of your scheduling and format.