2 Zingel
Did I understand you correctly that the AI didn't manage to capture a single town???
Because my Warlock and Sorceress captured one town each, and on day 15, the Barbarian captured 2 towns. In the end, it took 16 days.
In my previous attempts, by day 14, everyone already had a town.
So, I even had to wait until the end of the week to kill them all - I didn't have enough strength. Total - 15 days.