With a growth rate scenario of 4% per year, all accession countries would reach by the year 2026 the same income level of Greece when it joined the EU in 1981, namely 62.4%.
If I look at the level Greece had reached when it joined the euro zone twenty years later, then it would take the accession countries about to year 2033 before they would be at the level of the country with most catch-up need that has so far joined the euro zone.