Before the instant of big-bang, time was expanding. Time was beating so fast that it didn’t have any interval. Time had infinitude as it is neither a scalar nor a vector and didn’t have any beat or rhythm which settled in at the instant of bing-bang. Big-bang could be viewed as a hole when time perceptibly acquired a magnitude like coming from infinity, traveling infinite intervals it had no interval while at big-bang time finally acquired a quantity or an interval. Infinite time means infinite mass was moving at infinitely small speed but at infinite distances and all the matter of galaxies pre-existed and came together at the instant of big-bang to move through the infinitely small hole that time acquired a beat or rhythm and space was born.
So big-bang was not the birth of matter but the birth of space. If in space, time contracts when approaching the speed of light, then at the infinite time, time is expanding without any space. The Big-Bang indicates time acquired an interval.
Time could be viewed as eternal not in the sense that it does have infinitude in front of it which in any case would be a quantity, that time had infinitude prior to that it had a definable quantity.