Its always difficult to say how long it will take the review team to get around to your book.
You should be aware that they may find issues with your book and notify you that it has a "ticket". The ticket should indicate what needs to done to correct the issue and be re-delivered using the same Vendor ID and files ( now corrected).
IF your book is OK at first review, you will see the red dot under your book in iTunes Connect change to green.
Usually before that you will have an email to notify that your book as been passed to the iBookstore. After that it can take - 7 - 14 days before you will see it "online". BUT there have been reports here that books have gone through in hours rather than days.. so its really a case of "wait and see" and be patient because it can be frustrating waiting... but it will apear eventually.