I would rather it be on Monday, and here's why: that way, you can put some polish on your manuscript over the weekend! That seems to be a lot more practical than actual Saturday submissions.
Beyond that, Avalon should post up his submission topic. Once we determine the exact date of submission, then he can proclaim which day of the week would be the deadline for applications for submission would be. (Mmm, that sentence is a bit wordy, but instead of revising it, I think I will just let you try and make sense of it)
One note about the "applications": I don't imagine Raethe and I would actually refuse someone if they wanted to submit. As of now, with this smaller group, I think it would be acceptable to have everyone submit whichever week they wanted. New members have seemed to subside for the time being. Plus, I think everyone has gotten good critiquing from multiple people on their submissions thus far, so all things considered, RE is going very well.