I think 2 weeks is generally more appropriate. It depends when you need a final count to your caterer/venue. Our caterer wanted 7 days notice, so we asked for the responses to be in 2 weeks early. This gave us an extra week to contact anyone that didn't respond.
Around 2 weeks before you need your final count for the venue or caterer.
My new bff Gayle Forman!
?You can have your wishes, your plans, but at the end of the day, it's out of your control" - Gayle Forman