So I've just started using the Galaxy Beta and am downloading the Witcher 3 and noticed that there will be achievements so I wanted to know if these would be available on May 19th or if the achievements will come at a later date?

It's Preloading of The Witcher 3.
Which means you can not play it before May 19th first day update.
So, achievements will be available on May 19th.

I was wonderin why there is no achievements for other games yet or am i missing something ?

Games have to push out a new update in order to support achievements.
I think Witcher 2 will get a new build to support them.
Witcher 3 will support them at launch.

I don't know if Witcher Adventure Game already unlocks achievements or will need an update aswell.

Thanks for your reply and I do understand already that the game is only pre-downloading - sorry maybe I was not clear in my post when I said "if these would be available on May 19th or if the achievements will come at a later date" - My question is only about achivements and NOT about playing the game before the 19th. This is the Galaxy Beta so I'm not sure if achievemnts are even working yet? So does anyone know if Achievements will work on the witcher 3 on the 19th May? or are you just speculating?

Yes, Galaxy already has achievements support built in and The Witcher 2 is one game that has support. Witcher 3 will as well, and more games are likely to be updated by their publishers over time as well as other new games coming to the catalogue.

To be clear Witcher 2 has them, but I don't think there functional yet...