Suppose a person is organizing a group get-together centered around a specific popular cultural event occuring on a weekend. A good many people have been invited (20-25, not including children), and consequently the host needs appropriate time to prepare for the event. The host will be preparing a limited menu from the grill, as well as accompanying items such as salads, dips, chips, etc... Obviously, the supplies (cups, plates, etc...) will need to be purchased as well.

What do you think is an appropriate RSVP date in relation to the event, with the understanding that schedules are often unpredictable given the presence of children and related family issues?

a week?

is the superbowl coming up?

3-7 days sounds realistic.

I think a week is the minimum. Remember that the game is on Sunday, so telling the host 3 days before means telling him on Thursday which, given shabbos, isn't a whole lot of time to prepare. Telling him the Sunday before at least gives the host that Sunday and time during the week to get things together. Although, many people are busy during the week and doing extensive shopping then can be difficult. That is why I would suggest 2 weeks notice. However, I could understand 1 week. Running things down to the last few days (without good reason) is poor form.