There is really no necessity for Christians to be concerned with the ultimate (i.e. metaphysical) nature of Time; but they often have been, especially when wanting to think or talk about eternity.
(Eternity might be thought of as time from God's perspective; or time as it really is.)
There seem to be two options - either to regard eternity as something different from earthly mortal time, or as something essentially similar to earthly mortal time (and which transcends or contains earthly mortal time).
Earthly time is linear and sequential change; so if divine eternity is different from it, then eternity is seen as simultaneous rather than sequential, and about the absence of change.
But Christianity is all about change - not least because love entails change; or, at least, love is dynamic and sequential if it is accepted that relationships are the key metaphor for Christianity (God as Father, Jesus and ourselves as Sons of God; the primary commandments being love of God and neighbour; the Apostle John's definition that God is love - and so on).
So, if it is decided that ultimate, divine reality is simultaneous and static, then the core metaphor of Christianity is demolished; Eternal Heaven cannot be imagined as a place of ultimate love if Heaven experiences no real change.
Yet, if we regard divine time as being, like earthly mortal time, a matter of linear change - then there are problems of another kind. The idea of reality as un-endingly changing, or evolving forever, with no end-point and no cyclical recurrence, is pretty-much as alien to human nature and common sense as the idea of unchanging simultaneity.
The difficulty of squaring Christianity with eternal evolution and time as linear and sequential is that change is destruction, as well as building. How can things change forever without end or ending, without destroying everything sooner-or-later? It becomes hard to imagine that eternal change really is eternal progress; because here on earth our experience of perpetual change is usually destructive of meaning and purpose and associated with inversion of values - as with the senseless round of styles and fashions, or the existential horror of 'perpetual revolution'.
So, in my opinion, while I tend towards the idea of Heavenly Eternity being of the same general nature as earthly time (i.e. I believe that all time entails linear sequential evolutionary change) neither of the metaphysical concepts of time are really satisfactory from a Christian perspective; both can answer one set of questions only to generate a further set of questions; both will - if taken to be axiomatic and followed through - tend to dismantle Christian revelations concerning the primary nature and purpose of reality.
The only answer I can come-up-with - which is more of a change of subject than an answer - is that if we accept relationship as the primary metaphor given us by revelation; then the model for eternity is one of families and their generations in a progressing situation of ever-more, open-ended, increase in quantity and quality and complex interaction of loving relationships.
In other words the universe of reality is an ever enlarging and ever more extended family and family of families; and what binds them and gives primary meaning is loving relationships as they emerge, grow, interact through time. Nothing repeats, complexity grows, direction and objective progress come from the absolute and unchanging nature of love.
Reality begins without love, and love increases through time, and this process is eternal in the sense that we cannot imagine any point at which it must (or should) stop - so long as increase of generations continues, and each individual chooses to live by love, then there is always scope for more love than currently exists, and new configurations of love.
So eternity is seen from the inside, from the perspective of individual consciousness (whether human or fully divine in God) as the absence of an absolute limitation on the increase of love; rather than as if from standing outside of reality, from which stance eternity seems like a containing and limiting and static sphere.
Note added: I just found quoted a passage from CS Lewis in The Allegory of Love which says (albeit about something else!) what I was trying to say about our experience of eternity: [Man] does not through phases as a train passes through a station: being alive [Men have] the privilege of always moving yet never leaving anything behind. That is what, somehow, our understanding of Time must encapsulate. Lewis tried to explain how nothing is lost from the perspective of static simultaneity - which is somehow also experienced as open-endedly dynamic; I would try to explain it from the perspective of unending linear sequentiality which is somehow also able to achieve permanence. Lewis's Platonism views things from an imaginary stance outside the train; mine from the imaginary perspective that there is no outside and all is seen from within the carriage. But 'somehow' 'always moving but never leaving anything behind' is what must be explained...