Get my 1st Gardevoir?

Sure! She's a great attacker and defender. I have 2 that have seen plenty of use. You'll still be able to get 3 or 4 more during her eventual CD

Evolve only if you desperately want the dex entry.

You have no candy to power it up, so it likely won't be that useful to you. So if you want Gardevoir for actually using it, you should wait. You might get a better Kirlia from the next weatherboosted raid.

Is your Kirlia male or female? Looks like level 25.

I wouldn't. Mow that meteor mash metagross is out, gardevoir's spot on defense was taken from it. on offense its a hard machamp counter only agaisnt nonsteel moves. Id hold onto it for now