Don Carson says on John 2:12
John is often accused of anachronism, of reading back into the time of Jesus events and beliefs that developed only later. This is singularly unlikely. No evangelist is more persistent than John (at least sixteen times) in carefully distinguishing what the disciples understood back then (during Jesus’ ministry) and what they understood only later.
Here are 10 such texts:
1. Joh 2:22 After he was raised from the dead, his disciples recalled what he had said. Then they believed the scripture and the words that Jesus had spoken.
2. Joh 12:16 At first his disciples did not understand all this. Only after Jesus was glorified did they realize that these things had been written about him and that these things had been done to him.
3. Joh 13:7, 19 Jesus replied, "You do not realize now what I am doing, but later you will understand." ... "I am telling you now before it happens, so that when it does happen you will believe that I am who I am.
5. Joh 13:24, 25 Simon Peter motioned to this disciple and said, "Ask him which one he means." Leaning back against Jesus, he asked him, "Lord, who is it?"
5. Joh 13:36 Simon Peter asked him, "Lord, where are you going?" Jesus replied, "Where I am going, you cannot follow now, but you will follow later."
6. Joh 14:5 Thomas said to him, "Lord, we don't know where you are going, so how can we know the way?"
7. Joh 14:29 I have told you now before it happens, so that when it does happen you will believe.
8. Joh 16:4 I have told you this, so that when their time comes you will remember that I warned you about them. I did not tell you this from the beginning because I was with you
9. Joh 16:17, 18 At this, some of his disciples said to one another, "What does he mean by saying, 'In a little while you will see me no more, and then after a little while you will see me,' and 'Because I am going to the Father'?" They kept asking, "What does he mean by 'a little while'? We don't understand what he is saying."
10. Joh 20:9 (They still did not understand from Scripture that Jesus had to rise from the dead.)