Our prayers are granted as soon as we have prayed, even though the process of fulfilling our requests has not yet begun.
When God will have any great matters done, he sets his people's hearts to work at prayer by a kind of gracious instinct. He stirs them up and moves their hearts by the influence of his Holy Spirit.
Where God gives opportunity for preaching it is more than likely that he has some people to convert. Usually the Word of God takes root among some, though often in but a few.
Ask God to make you like David: an intercessor, even in the midst of your own great sins and great needs.