1st testing period was 2 weeks ago (4/25-4/27)
2nd testing period (5/9-5-12)
I'm guessing the third will be (5/23-5/25), which is 2 weeks after this current one. Then there's the possibility of one final testing server to sum it all up and then, the release. :P
That's just my opinion-thought anyways.
Probably not this Wednesday since the test server notes mentioned that there is at least one more testing session still to come.