My understanding is that there is a dead period for 2 days immediately before and after the early signing period, which I believe ends on 11/22. After that, it's a quiet period.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .