If you are having an event on 5/12 and responses are due on 4/28 when should invitations be sent out?

Answer 1

If it is a formal event like a wedding or an event that requires a person to plan in advance for travel or formal wear - 4-6 weeks in advance.
If it is an informal event with local people attending 2-3 weeks in advance.

If a mixture of out of towners and locals have to attend - notify the out of towners by phone and send the invite at the same time as locals.

Answer 2

4/1 because 4/28 and 5/12 are 2 weeks apart so the intites and 5/12 should be 2 weeks apart.