I'm in a game and really don't want to die early lol so my phantom is p lvl 6 so are a few rebel ships I have advanced cloaking device when I attack before rebel do I get to cloak before they attack too

If you have initiative and attack before the rebels of the same PS then yes, your advanced cloaking device will trigger and you can cloak before they shoot.

O.k., it's a little difficult to parse your question, first off. Punctuation and Formatting are helpful!

That being said, if you have Advanced Cloaking Device, you cloak immediately after attacking, before any other ship attacks.
If their ship has a higher pilot skill, or the same and they have initiative, they get to shoot at you without your bonus agility dice.

Otherwise, you're golden.

And yes, it goes REALLY well with Veteran's Instinct, precisely to cut that window of vulnerability by a large portion.

Before the Decloak shift, VI's synergy also extended to being able to dodge arcs with the Decloak as well.

This was so super-powerful that only high-PS turreted ships could stand against it, and then the turret-players figured out how to make them too tanky for Swarms to hurt, which were also hopeless against the VI ACD Phantom.
(4 dice of agility vs 2 dice of attack. Who wins?)