Jerry Hill, again, in his book about their work in Guatemala, which I’m enjoying:
A chain of events like this begins with someone preaching the gospel. It is predictable that important reactions will occur. It is impossible to know what they will be, whom they will involve or where they may lead. The preacher will be disappointed at times that his plans for certain people in certain places were not realized. But he will be elated many times over when the unpredicted events bring in people, at places, and with results that no one foresaw. I believe this is fundamental to preaching the gospel to all the world in each generation: preach, and follow the leads! p. 44.
Great advice! God will open doors that we never dreamed of.