The servers are not open and it will take a lot of time before they'll be permanently open since there's still a lot of work to do in the game. Just to make you understand, we are still in pre-alpha stage, which means that we are not even at the alpha yet, so yeah, lots of work.
Regarding when they'll be open, we don't know. We don't plan a date for the stress test but a date that is decided after there was a bit of improvement in the game. In this you, other playing the game, you can test it, and we can see if there's something wrong that needs to be fixed so we can improve.