If we assume that in 8000 our religious landscape and scientific knowledge will be substantially different (hint: it will), we’re going to need a few more digits.
Already today we can use the Holocene calendar https://en.m.wikipedia.org/wiki/Holocene_calendar but in 8k years we might have an accurate and useful measure to specific points that are easier to work with / more valuable.
Perhaps the unix epoch might even be the most significant start time.