Other half says that now till Christmas is a good time to build the round up. Week before Christmas they all panic because they don't want their family to think they are dirty. Ideal time to push for cleaning insides as well. If it's a one off just increase the prices.
Also good time for gutter cleans.
Now that kids are back at school and holiday over then now's the time to get going. Alan thinks that August is the worst month as they are all on holiday.
Sure you get fewer takers Jan/Feb but windows get horribly dirty and thats when some window cleaners have packed it in because they can't deal with the cold.
In other words - go for it