whoever hears my word and believes in the one who sent me
has eternal life and will not come to condemnation, but
has passed from death to life.
So according to John those who hear and believe
Have (present tense, already, now) eternal life, and
have passed (past tense, already finished) from death to life.
If John is right, for those who listen and believe, passing from death to life is not off in the future. By the grace of God we live the new, eternal life here and now. True, we don't have it in its fullness yet, but we have it.
The hard part it seems is the hearing and believing. That is the constant struggle. Sometimes we either don't hear or don't even want to hear. Other times we hear but don't believe. We choose to either believe the culture or believe ourselves. We hear the truth of the gospel but choose to believe what we like. In doing so we risk throwing away the gift of eternal life.
Hearing and believing are ongoing challenges. We must immerse ourself in the words of Jesus and believe. Then, according to St. John's gospel, we can live in the new life Jesus offers, right now.