Question: what age is mid twenties?
Answer: Colloquially, 24 to 26 is considered to be mid-20s, with 23 being somewhat borderline (because of lower-end skew, see below). Alternatively, if you want to make the argument that 20 doesn't really qualify as "early 20s", you'd end up with early: 21-23, mid: 24-26, late: 27-29.