I view Squire as a risk-free village. It's worth buying on the first turn, and it's ok to over-buy compared to how many terminal actions you have. If you don't need the actions, you take a silver instead, not a bad deal.
The big question is, when am I going to need that much +buy? The obvious answers are Gardens and Goons, but cost-reducers also come into the picture. Squire combo'd with highway, bridge, or quarry sounds like it can 3-pile a game in record time.