Your response rates will vary depending on how many invitations are being sent and what other marketing your church is doing in the community. Unlike Christmas or Easter invitations, a new mover invitation is not targeted at a specific or time-sensitive event, so visitors may not respond immediately - you may see more of a trickle of visitors over several weeks. However, that does not mean that your invitations are not effective: studies show that it can take up to 7 "touches" before someone responds to a marketing campaign, so as you continue to promote your church through other postcard mailings, door-to-door invitations, special events etc... you will see higher response.
Even if just one family were to join your church from a New Mover invitation, you would still recoup your investment. Here is how it works: Studies show the average church attendee gives $1000 per year, your investment in the New Mover program is $948 per year if you send 1200 invitations per year at 79 cents each. That makes using the New Mover Program practically risk-free!