When is the best time to take bird houses down for the winter in the northeast or should they even be taken down at all?

In the UK, Bird protection law permits the cleaning out of nests between 1 August and 31 January. They meed to be taken down and cleaned out (and possibly disinfected with an approved bird friendly disinfectant such as Ark-klens or Tamodine-E, followed by thorough rinsing and air drying before repositioning).

See the related link below.