I go to Ikea a lot lately. I have several projects I'm working on that I'll unveil soon that will explain why! I always notice that people pull out papers and pencils to write down where to pick up their furniture. Here's a quick tip for my smart phone owning friends:
I take a picture of the item and its name and then the self serve tag. When you get to self serve you can pull up the picture! If for some reason the item isn't where it's listed on the tag (this happens more if you pull up its location online than when you reference the in-store tag) you can pull up the item's name/pic on your phone. Usually the isle's don't change often, but the bin is the mismarked number. You can use the item name/picture to quickly scan the isle and find your item! I hope this helps! It helped me this week!