If you've got shelving or a cupboard that is suitable for monthly collections, don't try to change all of the food from one shelf to the next, just change the labels. Find some kind of label system that you can attach to the shelves (above or below) and be able to move.

Simple way: Got some old plastic 1" venetion blinds? Cut them into 4"-6" lengths and write a month on each one. Apply Velcro to the back of each one (soft fizzy side of the Velcro). Apply the hook side of the Velcro to the edge of the shelves. When you want to 'rotate' your food, just move the label.

Sue