Hi, at what point do you fit the mouse gaurds to the Hives
When it is likely that mice are going to need somewhere warm and cosy to sleep and the bees are clustering at night......so season and weather dependent.
Mid/end October ? November?
If it is mild and the bees are still foraging on the ivy they won't let any mice in.
Best still is to have an underfloor entrance so you don't need a mouse or wasp guard at all.