Blizzard has announced on their Developer Update Livestream that players will get another chance to play Diablo 4 on May 12-14 before the game releases on June 6.
Diablo 4 Developer Update Stream – Liveblog Summary Diablo IV Post-Beta Changes
The Diablo 4 Stress Test will last for 48 hours from May 12-14:
Start: May 12 at 12 p.m. PDT
End: May 14 at 12 p.m. PDT
Experience the post-Beta changes Blizzard has implemented since the Open Beta period in March.