John 4:35 Say not ye, There are yet four months, and then cometh harvest? behold, I say unto you, Lift up your eyes, and look on the fields; for they are white already to harvest.
36 And he that reapeth receiveth wages, and gathereth fruit unto life eternal: that both he that soweth and he that reapeth may rejoice together.
37 And herein is that saying true, One soweth, and another reapeth.
38 I sent you to reap that whereon ye bestowed no labour: other men laboured, and ye are entered into their labours.
Clearly, during His ministry on earth, Jesus did two things: he prepared multitudes to receive His message, and He prepared His small team of "reapers" to enter into the fields where He had labored, and reap the harvest that He had prepared.
Clearly the Samaritan woman acted as Jesus co-laborer in announcing Him to the whole country-side as the Messiah.
Notice also that Jesus also prepared the disciples for their future ministry by His own life and His example, His way of teaching and reaching the Samaritans, which they were able to observe at first hand during the next two days.