The Experts @ChurchFuel gave us some great information:

Instead of trying to develop a strategy for asking your people to invite others all the time, focus all of your energy and resources on a big day or event.
You can use a holiday or you can create a special Sunday just for invites. Call it "WELCOME" Day if you must, but just be sure it's like no other day on your membership calendar.
Lead up to your special day with a series of well planned messages and online activities. Challenge your entire organization to get involved and be sure you have a process or plan to appeal to people on that special day. Make sure EVERYONE in your organization knows what’s coming and what the outcome should be.
REMEMBER the "future is in the follow-up". So be very prepared to then follow up on your big day. Have another process in place, ready to reach out to each person who attended and personalize the outreach to show each individual how they can benefit from forming an alliance with your organization.
Do you have a written plan? ....Why do you want them in your organization? Why would they want to be in your organization? There should be no guessing and your presentation should be professional.
If you'd like to start creating plans for a "Membership" day and a follow up plan....or any other of “Growing Your Membership” recommendations, select a day and time on my calendar to discuss it!