40 CFR § 280.243
Timing of operator training
June 9, 2020
(a) An owner and operator must ensure that designated Class A, Class B, and Class C operators meet the requirements in §280.242 not later than October 13, 2018.
(b) Class A and Class B operators designated after October 13, 2018 must meet requirements in §280.242 within 30 days of assuming duties.
(c) Class C operators designated after October 13, 2018 must be trained before assuming duties of a Class C operator.