Here's an interesting post by Alan Kurschner:
Premillennialists and amillennialists agree with each other that the thousand years reference denotes a temporal period, that is, a historical period. What we disagree on is when it will begin. Amillennialists think it started at Christ’s first coming, so they view it as interadvental, that is, between Jesus’s first and second coming. Premillennialists on the other hand think the millennial period will begin in the future at Christ’s second coming, so they view it as postadvental.
i) There are amils who identify the millennium with the intermediate state. The logic of that position means the millennium antedates the first advent of Christ. If the millennium is conterminous with the intermediate state, then that goes all the way back to the antediluvians. Abel would be the first person to enter the millennium. The first saint to die and thereby pass into the intermediate state.
ii) It might be argued that while the millennium/intermediate state isn't chronologically coordinated with the first advent of Christ, it's teleologically coordinated inasmuch as the merit of Christ retroactively saved OT saints.
But I want to address another view on the millennium. There are some interpreters who think that the thousand years reference does not denote a period of time at all, so they would hold to a non-temporal construal of the thousand years reference. Typically they would read an exclusively symbolic meaning of the expression, for example, referring to the victory and vindication of the saints. So for these interpreters they would see the fulfillment of the millennium occurring not in the course of a period of extended time, but only thematically, at the second coming of Jesus.One of their key arguments against a temporal interpretation of the millennium (pre-, post-, and amillennial) is to point out that numbers in the book of Revelation are symbolic, that is, we should not take them literally (e.g. 144,000). I would argue against this because there are clear examples that this is not the case (e.g. John wrote to seven literal churches), so we should not make sweeping blanket statements when it comes to numbers in the book of Revelation, which seems to be the case with many interpreters. Leaving aside this point, I want to reply to this objection by making a different point.
i) That argument either proves too little or too much. For instance, Preterists identify Babylon as Rome since any 1C Mediterranean reader would recognize Rome as the city of seven hills (Rev 17:9). Yet Alan is a futurist.
ii) Even in a scheme where the numerology is purely symbolic, odds are that every so often a symbolic number will coincidentally match a literal counterpart. That's statistically inevitable since there will always be 2 of something, 3 of something, 12 of something, &c. For instance, Rome isn't the only city with seven hills.
iii) Although there may have been seven literal churches in Asia Minor at the time of writing, were there only seven churches? Even in the same city you might have more the one house-church. So how do we count them?
Was each letter sent individually to each church? Or were the letters bundled with the rest of Revelation and distributed to all the churches within John's purview? Every church which had a copy of the Apocalypse heard all seven letters read aloud. Is that just seven churches? The seven letters appear to be integrated with the Apocalypse as a whole, so it seems unlikely that they ever circulated separately.
iv) As one commentator notes:
Next is the flow of time within the visionary world…But in the visionary world this "short" period extends from Christ's first coming until his final return. Visionary time does not correspond to chronological time in the readers' world. Revelation was written decades after the death of Jesus, yet the entire period of the church's conflict with evil fits within the three and a half years of visionary time (11:2-3). C. Koester, Revelation (Yale 2014), 120-21.
Back to Alan:
In the book of Revelation, when it comes to these non-temporal interpreters, they will agree that—not all numbers—but the particular numbers which designate temporal periods do in fact refer to historical periods of time. For example, designations such as “ten days” [2:10], “short time” [12:7–10], “three and one-half years, 42 months or 1290 days” [11:2, 3; 12:6, 14; 13:5] are typically interpreted as symbolic by virtually all of these interpreters, but, they also would view them as indicating historical periods of time, not necessarily the literal designation, but nevertheless, a period of time (e.g. “42 months” is symbolic of the church age, they will claim; yet the church age by definition denotes a historical period of time).My question then is why would all these other references to temporal designations in the Apocalypse refer to actual temporal, historical periods (and also possessing symbolic meaning), but the reference to the thousand years is singled out as a non-temporal period? Just like all the other temporal designations, why can’t the thousand year reference also denote both a symbolic meaning and a temporal meaning? This does not require the interpreter to think that it refers to a literal thousand year period (though I do not think there is reason to think it does not refer to a literal thousand years), but at least it could indicate an undetermined period of time.
i) A radical position might classify Revelation as literature, like Perelandra. Or like a movie. In a novel or movie, the flow of time is subdivided into a series of episodes. There's what the periods represent in plot terms. But they don't represent anything outside the fictional world of the movie or novel.
That's not my own interpretation. I simply mention it to draw attention to a potential objection.
ii) One issue is the need to distinguish visionary time from real time. Revelation is like an extended symbolic dream. The dream is episodic. The question is what those correspond to in real life.
iii) As timebound creatures we necessarily experience reality in temporal intervals. The real question is not whether the millennium is temporal, but whether the episodes in Revelation chart a unilinear sequence of unrepeatable events. Does real history (past, present, future) run along a parallel track?
An alternative interpretation is to construe some of these episodes as stereotypical kinds of ordeals which Christians at different times and places may experience. If, say, the millennium represents the intermediate state of the saints, then believers enter the millennium at different times because they die at different times throughout the course of human history.