Have you ever asked a potential ministry partner for a "One Time Gift?" Read this article on why you should banish that phrase from your vocabulary!
Because you don't really want a one-time gift. You want a "special" gift.
If a person (or group) who is interested the ministry doesn't want to make a commitment for regular giving, they often will respond to an appeal for a special gift.
But, we should not call them "one-time" gifts. That person may want to give another "special" gift in the future, and if we call their initial gift a "one-time" gift, we may be hinting "I'll never ask you for another gift again. This is a "one-time" appeal."
So, while the concept is valid, let's just not use that phrase.
And I have found that often my "special" gift givers become regular contributers ... sometimes committing a regular pattern of giving, but sometimes preferring to respond to special needs and special appeals.
Keep your options open.
Drop the phrase "one-time-gift" from your vocabulary.