The second cup of wine is not mentioned in the gospels. It is the cup of plagues, drunk after the Passover story is told but before the meal.
At the point where bitter herbs are eaten, Jesus revealed that He would be betrayed by Judas: The one who has dipped his hand into the bowl with Me will betray Me [Matthew 26:20-25].
The third cup of wine is the cup of redemption. This is where Jesus announced the new covenant, for the forgiveness of sins [Matthew 26:27-28].
He did not drink the fourth cup of wine the cup of completion. (He poured it out, Luke 22:20) He said that He will drink that cup with us in heaven [Matthew 26:29] at the marriage supper of the Lamb.
Ooooh so close yet so far. Did you either listen to or read the link I gave you to Scott Hahn's Fourth cup?
Thank you for sharing your insights, dear brother in Christ!