"For my Father's will is that everyone who looks to the Son and believes in him shall have eternal life, and I will raise them up at the last day." John 6.40
Getting your head around "eternal life" is not easy! Maybe it will help to tease out the different categories of time, which are mentioned in the Bible and which we encounter through experience. Time, as we know it, is linear: one thing happens after another and that gives us our perspective on life as past, present, future.
Can it always have been this way or, as with everything else in the universe, must there have been a starting point? Many religions, including Christianity, posit a Creator. Christians assert that this Creator, whom we refer to as God, not only created the world but that he sustains it. That is, he remains actively involved in its flourishing and development. And, indeed, we would go on to say that he will redeem it from its vulnerability to decay - but that is another story.
Back to the question of "time". If God created everything, then that includes time which means God exists outside of time, in the realm we call "eternity": that which is without beginning or end because it always is. It is important to distinguish "eternity" from "everlasting life". We understand the latter, "everlasting life", as being a gift from God which, although it will have no end, has a beginning: the moment God grants it.
But, when a person dies in faith and goes to be "with the Lord", does that not mean they now abide beyond time, as we know it, in that realm beyond time, where God is? That being the case, their "everlasting life" now knows no bounds. The exception to this is when Jesus entered our world and submitted himself to our earthly restrictions, in order that he might deliver us from their corruption. So Jesus is the ultimate exemplar of the clash between time and eternity. But there are rare occasions when that paradox is reflected in other situations - in the appearance of Moses and Elijah with Jesus on the Mount of Transfiguration (Matthew 17.1-13) or the judgment of Ananias and Sapphira (Acts 5.1-11) to mention two examples.
The juxtaposition of time and eternity may also explain the apparent contradiction between Jesus' promise to the penitent thief on the cross (Luke 23.43) and the final resurrection, which has yet to happen (1 Thessalonians 4.16). And it also explains how we can encounter someone destined for eternity, while still in their earth- and time-bound state. That is to say, we are glimpsing them as they will be "in eternity" rather than as they are now "temporarily".