1. Determine date, time, and guest list
It's Monday. This party was born of spontaneity: no big occasion, informality, short notice; how about Susan & Mel, Steve & Deirdre and John & Martha on Friday night at 6:30?
2. Send out invitations
5 days 'til party necessitates phone calls or emails. Informality calls for invites to close friends who would appreciate your shopping skills or at any rate, you. If email, use clipart of a blue plate or shell to tie in theme. Don't forget to ask for RSVP.