Thanks for all the great replies. Looks like from your experience, we should get going a couple of weeks earlier than planned. It looks like it's a good idea to be out of the Great Lakes by end of Sept. or first week Oct. The crew taking the boat through the Lakes will consist of a group of fairly hearty North Sea sailors (which includes my husband) so cold weather and elements shouldn't be a problem, however, it's great understanding availability of diesel and marinas etc.
All additional thoughts are much appreciated!
Assuming we make it to NYC by late October, will that be a late start going down the ICW? If so, please send links to qualified, cheap shipping companies!