DoTA

CBT will most likely start at the end of March. Again most likely it will last during March and April.
All the beta will be divided into different beta events that will be supposed to test different things, thus you might be invited not for all of them.
If you'll be selected for CBT you’ll receive an invitation with instructions on your registered email.
Expect a download size of around 20GB.

1st CBT invitations started to send out on 03.26.2013.
If you haven't received it up until now then I guess you won't be in the first CBT, same as I won't.