I too have a question; this says the end of September? Was that a typo?? The next paragraph says November. I'd be interested too.
Sign Up list
There is no deadline so you can sign up at any time during the 2 months as this will be just an intention to participate. When you have made and are ready to mail your runner you can then sign up to the “ready to mail” list which is binding.
But please remember that the only list that counts is the Ready to Mail list at the end September