Perhaps in one week? Personally, it takes me anywhere between 3-16 days to fully digest a book - no clue where other people stand on digestion. While I am not an actual participant this time, I'm offering speculation.

Also, by having a "wrap-up" thread, you could invite people who are familiar with the book that did not feel like rereading it. Those people would then be able to share their thoughts without worrying about spoilers. Granted, they could just do that in this thread, but this thread is specifically for the final chapters.