On the day of your blog tour appearance, open with a short statement, recapping the themes expressed in your book excerpt, and ask the blog audience for its reaction. Depending on how the blogger administers the site, you may be given a login and password for the site, or simply e-mail your material to the blogger.
Reaction from the blog audience can continue for several days, giving you the opportunity to reappear, replying to comments and answering questions.