You never know what good you are doing by "planting seeds", and somethimes it is successful straight away.
My youngest son was offered a Bible Study by a keen young M.S when my son was in his mid-teens. When they covered the bit about the Flood, my boy asked so many awkward questions, bless him, that the M.S went away muttering , "Well if it is true, there had to be an awful lot of miracles to make it happen!".
After this debacle my son decided the JW religion was not for him. That M.S is still in I believe, but even he cannot believe in the W.T version of the Flood.