I prewash all my fabrics and then wait until after everything is done before I wash large bed quilts.
However, I do "block" all my wall hangings and some smaller quilts before I bind them to make sure that they are square (or rectagular). Leah Day has a info on her site about blocking quilts and you'll also find info on youtube.
Before binding I soak the quilt then spin it in the washer. Then I pin it up on my design wall which also serves as a blocking wall. I make sure it is smoothed flat and square and put pins into the board every couple of inches to hold it in place. Then I put a fan on it overnight to dry it. When it comes off, I do a little trimming and then bind. They come out pretty much perfect with that method and I suspect Geta is doing something similar.