Summarize this article in one sentence.
The invitation must include the following information:  The address/where the party is Day of the party and time it begins Drop off and pick up times (see above) What to bring (pillow, blanket, costume, makeover goodies, DVD, etc.) RSVP (how your guests contact you to say if they can come or not). That includes your email address and phone number. It's fast, it's easy to track and most people are not the slightest bit surprised to receive invitations via emails. Just be sure to offer the option of calling you as well as emailing back, as some parents will still prefer to talk to the household parent or guardian in person.

Summary:
Mail invitations one to two weeks prior to the party. Consider using email to send out the slumber party request.