My builder has been nothing shy of great to work with and the stuff I am handling seems to all have fallen into place without skipping a beat (probably more luck than anything on the last one). My excavators are good friends who are slow thru the winter and early spring so they are able to jump right in when I need things done, for the most part.
As for my situation, we put our current home on the market about 3 weeks ago and have not been as lucky as you. We have had a handful of showings, including one this evening and the market is starting to pickup from what we are told so we will see. At this point, if it were to sell and our house is not ready by the time we need to get out we do have a place to stay otherwise, timing may work our perfect for us to move right into the new place.
Good luck with your building, for me it has been fun and any horro stories have been truly self-inflicted!