Currently you are only able to offer up your lunch (or take someone else's offer of a lunch) within the current week.

Previously this has not been a problem since lunch was ordered week-by-week. Now we are ordering lunch for a full month at a time.

Use case:

It's thursday and I have just been asked to join a meeting on monday that requires me to be at the office. I would like to know as soon as possible if I can expect to have a lunch at the office on monday.