Hey, dazed.
For Etihad recruitment days, Etihad always lists their assessment days on their website. If they are going to recruit more people, then they will post a schedule on their website. Any other company that has information about assessing candidates may or may not be affiliated directly with Etihad.
If you're talking to a company, and not directly with Etihad Airways, keep in mind that the company you're talking to is honestly working with Etihad. There are some less-than-honest companies out there. The best way is to complete an application at Etihad's website.
Good luck to you if you attend an assessment day!!! I've tried once and I'll try again!!