When will I be able to change my June 2017 test to Sep 2017?

Hi everyone,

I saw that May 16th will be our last days to change the date of June 2017 test. I also see that the registration for Sep 2017 test is not available yet. Does anyone know when we will be able to start changing date? I am worried if I will miss the day of changing date.

Thanks!!

Alison