God knew the plan .. but Jesus did not. Jesus had to trust in God also .. just as we do.
Jesus only knew he was to be crucified .. He did not know the rest of the plan. It was a secret. God could not take the risk of Jesus revealing the plan ahead of time - if it had been revealed - the devil would not have killed Jesus - and you and I would have no way of reaching heaven.
I guess that's why I never have any trouble trusting God to come through in the trenches. Just when it looks like everything is lost .. God is there to cause miracle after miracle to take place.
To get an understanding of this - read about the Jewish wedding ceremony - it gives a lot of clues. After the engagement, the bridegroom goes to build a home for the couple .. but the wedding day is a secret. No one knows when the day will be - only the Father. When the time is right, the Father tells the son - go and get your bride. I believe this is why the Bible clearly tells us that no one knows but the Father when Jesus will return for the church.