One thing I noticed when rough-cutting my 10-1/2" x WOF strips is that some of my fabrics weren't a full 42" after the selvage is removed. Theoretically a person should be able to get four 10-1/2" squares from one WOF of fabric, but in some cases, I'll only be able to get three squares. I guess some manufacturers like to "be frugal" when it comes to the width.
I would be able to get four 10-1/4" squares, though. Is that close enough? If not, it's perfectly fine because I can use the leftover "short" piece for another project.
Either way, it's nice having the squares a bit oversized to allow for shrinkage and ruler differences.
Edited to add: The dates work for me either way, but there will probably be more folks to sign up if they have a little additional time.