A full month has 16 two-day periods. The City Construction Kit missions that I tested (Valentia, Londinium, Tarraco, Caesarea) had 16 two-day periods in the first month. But the career missions I tested had a short first month:
13 Tarsus
13 Capua
11 Lugdunum
13 Damascus
14 Londinium
Still learning after 20 years.
[This message has been edited by Brugle (edited 04-22-2020 @ 04:56 AM).]