Time relates to the human life, to earth. Eternity has no time. In the first 5 books of the Bible, (original Hebrew Scriptures) and in Psalms, it refers to “A day is as a thousand years” in reference to God and Eternity. If a day = a thousand years, the opposite is also true i.e., a thousand years = a day IN ETERNITY. We will not (I believe) be AWARE of time, in other words, in purgatory, we won’t be saying: ‘I came here in 2014, and now it’s 2016, so I’ve been here 2 years.’
I know that Mary said in an Apparition in Lourdes that a particular person who had died would be in purgatory “until the end of the world”. However, that person will not “count” time in years or days or weeks. The time in purgatory will just be the time in purgatory, regardless of the time in the physical world. Eternity has no time:
Therefore, we will not be aware of “time”, only of our repentance and purification, knowing that when it ends, we will be with the Lord in Eternity and in Heaven. Doesn’t that make sense?