There are errors in the released times for Oklahoma voting. According to Glenda L. Williams, Secretary of the Texas County Election Board in Guymon, Oklahoma, here are the corrections:
Early voting is available from 8 a.m. to 6 p.m. on the Thursday and Friday immediately preceding an election. Early voting is also available from 9 a.m. to 2 p.m. on the Saturday immediately preceding a federal or state election.
Early voting is not available on the Monday preceding an election.