I had 2 wish list books come through from the same person, before I could accept them she pm'd my saying she had changed her mind and was going to keep the books.  I ask her to cancel the orders so that I would remain first in line so far she has not done that.  If they time out will I go to the end of the line?????  They are still showing in my list of wish list books to accept

Don't cancel or you will lose your spot in the wishlist. If she cancels or lets it time out you go back to number 1 in line

She can't cancel until you accept them, so you'll need to accept them.  You'll keep your place in line when she cancels.

Yes, you have to accept them. Then she will be able to cancel or they time out and you go back into your spot in the WL line. If you do not accept them before the 48 hours, then she cannot cancel them and you will lose your place in the WL line.

That happened to me today. I accepted a WL book not long after they posted it. A half hour later, they cancel my request. I went back to the #1 slot and so will you if you let the poster cancel.

Why would they cancel so fast after posting?

Maybe they noticed something that made the book unpostable.  Maybe they remembered that they'd promised the book to an IRL friend.  Maybe their kid asked to read the book.  Maybe they hit "OK" and then noticed the ISBN was for the hardback and they had the paperback.  There are all sorts of reasons that someone might want to cancel.