Thinking of Converting Some Lawn to Meadow? 

The Xerces Society has a wonderful guide to organically preparing a site, whether an old field, public park or your lawn.

When is the best time to seed a new meadow? After the first frost, through winter, even on snow, until early spring. 

What is the best time to mow a meadow? After the first frost, but better yet to wait until March, so birds can use the seed heads for food through the winter. More information here.