I participated at the assessment day on 24th of January and after we were selected the waiting of the happy mail was very long. Some of us received the "happy to inform you" very soon but the other ones received nothing so we had to call to Etihad and ask what happend (till the end of March we had no answer). They told us that the happy mails were sent and they have no explanation for not reaching to us. So they remanded the mail to the ones who didn't received it.
I suggest you to call them if a long time pass since you were at the assesment and have no news.
Good luck for everybody and hope we'll get soon in Abu Dhabi!!!!