I love Bible Study!!!
I am going to go against the norm of the way this thread is going, but I believe He was referring to when they would see Him again after the resurrection, before He ascended into heaven.
He is directly referring to the statement He made and then the repeating of the statement in the form of a question by the disciples.
Jhn 16:16-23 "A little while, and you will see me no longer; and again a little while, and you will see me." So some of his disciples said to one another, "What is this that he says to us, 'A little while, and you will not see me, and again a little while, and you will see me'; and, 'because I am going to the Father'?" So they were saying, "What does he mean by 'a little while'? We do not know what he is talking about." Jesus knew that they wanted to ask him, so he said to them, "Is this what you are asking yourselves, what I meant by saying, 'A little while and you will not see me, and again a little while and you will see me'? Truly, truly, I say to you, you will weep and lament, but the world will rejoice. You will be sorrowful, but your sorrow will turn into joy. When a woman is giving birth, she has sorrow because her hour has come, but when she has delivered the baby, she no longer remembers the anguish, for joy that a human being has been born into the world. So also you have sorrow now, but I will see you again, and your hearts will rejoice, and no one will take your joy from you. In that day you will ask nothing of me. Truly, truly, I say to you, whatever you ask of the Father in my name, he will give it to you.
Jesus addresses their question by putting it back into a question Himself. So I believe it is safe to say that the verses following this interchange are describing the statement He made and the question the disciples asked.
Notice what happened after the resurrection. Not one question was asked to Him. But....
Jhn 20:19-23 "On the evening of that day, the first day of the week, the doors being locked where the disciples were for fear of the Jews, Jesus came and stood among them and said to them, "Peace be with you." When he had said this, he showed them his hands and his side. Then the disciples were glad when they saw the Lord. Jesus said to them again, "Peace be with you. As the Father has sent me, even so I am sending you." And when he had said this, he breathed on them and said to them, "Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you withhold forgiveness from any, it is withheld."
See, He gave them power, well...He gave them the understanding that they had the authority to do anything in His name.
"Truly, truly, I say to you, whatever you ask of the Father in my name, he will give it to you."