I just posted a book that is WL.  Usually when I do that it goes on hold immediately.  This one didn't, it went to my bookshelf.  If I click on my bookshelf on the book is says there are 189 WL waiting.

How long should it take to move to hold?  Thanks

it's probably just a glitch.  it should be requested soon!

It does that to me too sometimes.  I  think the first person at the top of the list has it an auto request.  So it waits an hour before actually requesting.  If you look on your bookshelf, there will be a gray circle to the fair right if that's what's happened.