I have a potential strategy. It is as elegant as it is simple.
Wait and see. I don't know about you, but December 15th feels like an eternity away (though, that may just be because I have so much freakin' work to do before that date will roll around). Therefore, it may be just a little premature to start uber-structuring this stuff before we even get the first submissions.
Oh, you wanted like an actual strategy? Well, that's good, because I have one of those, too! If Reading Excuses' growth increases at a constant upward rate, well, then obviously that would get extremely hectic very quickly. I think too many submission dates would needlessly complicate the process. Instead, how about we eventually subdivide the main Reading Excuses group into smaller sub-groups. A group of five, six, or seven is not difficult to deal with, and I think the main issue here is that we could have too many people/submissions to deal with in a single time frame. Well, sub-groups would solve that problem. It's less to keep track of, at least.
The problem with sub-groups would then be, how do we determine sub-groups? For this, it may just be necessary to wait and see how the December submissions go and roll from there.
Of course, there are a few problems with sub-groups. Firstly, if everyone is divided into their cushy sub-group, then that does not immediately "invite" new writers into Reading Excuses. I don't know about you, but I think the more, the merrier, here. The key is just to utilize the manpower (and fresh writers and ideas) in a coherent way. We don't want anyone to feel alienated.
One potential solution to the alienation issue is to rotate writing groups. That way, more ideas and feedback can get flowing. Unfortunately, this also has drawbacks, because for people submitting lots of chapters of a single work, it's not easy to just say "Oh, now the new subgroup gets to read this heap of pages!"
Since any of these potential methods have drawbacks, I think it would be better to just sit back through the December submissions and see how it goes. For all we know, the new people entering Reading Excuses could level off and we get a more manageable group to work with. Or, people might just look through their emails and pick the submissions they want to critique and by some miracle, it turns out that people are critiquing works at a pretty consistent amount, enough so that it would no longer be practical to divide in sub-groups.
We just don't right now. Let's wait a little bit.