has just published an FAQ
status from now until the beginning of the headstart period on May 30th. Dubbed "Ops Week," this period will see the team "testing various launch systems, practicing [its] disaster recovery processes, making sure [its] fail overs fail over correctly, and putting some extra testing on [the] final Release Candidate."
But you don't care about their problems; you just want to know whether you can log in. Yep! Carbine intends to make the servers available for play. Although uptime windows won't be announced ahead of time and some may be brief, players should anticipate server availability during business hours on the west coast. Open beta characters will be accessible for as long as the team can manage it before the inevitable wipes.