Not later than 90 days after a covered employee receives notice of the end of the period of mediation, but no sooner than 30 days after receipt of such notification, such covered employee may either—
(1) file a complaint with the appropriate agency, as determined under section 454; or
(2) file a civil action under section 1346(g) of title 28.
3 U.S.C. § 453 (2018)