Jesus simply says, "The hour has come that the Son of man should be glorified." To me without the cross meeting with these Greeks would not have the value. It would be on Old Testament terms. In chapter 11 verse 9 Jesus speaks of a twelve hour day. I believe His twelve hour day (typical) started from His birth to the cross. The cross was the final hour(the twelfth) when He would be glorified. Until the cross He could do these Greeks no valued good.
Now we come to the figure of a grain of wheat dying. When grain goes into the ground it rots and brings up one hundred fold. First of all Jesus is that grain of wheat. Just look at the results since the cross where He died.
Next, Jesus brings it down to us. We can represent Him as a grain of wheat. We die to ourselves and then we too can produce a hundred fold. If we love our lives to a degree that we want all the earthly pleasures to the expense of not producing anything for the Lord, there will be no lasting fruit.
I would like to spend the last bit of time on Philip and Andrew who the Greeks come on their quest to see Jesus. When Andrew came to Jesus he found Peter. When Philip came to Jesus he found Nathaniel. They are an interesting two people in Jesus plan.