We will be bringing down Star Trek Online on Thursday, May 17th from 0700 to 0900 Pacific Time (1400 to 1600 UTC) for maintenance. We will also be performing scheduled maintenance on the Cryptic Account system. During this time, you will not be able to manage Cryptic accounts. Please check the forums for more information.
Both the post and the launcher stipulate May 17th. Which is Thursday. It does state pacific time zone. It just doesn't state a.m. or p.m. Though this is usually done in the a.m. So I think that it's a safe bet to occur 7am through 9am tomorrow.