do yourself a BIG favor and buy test kits before you go!
these big events are notorious for having terrible quality drugs being sold there. ecstasy can be an amazing experience, dont sell yourself short by getting some stepped on BS from a stranger. you could also be sold chemicals that have a very different effect than what you intended--you could end up tripping balls for a day or two, you could wind up with straight meth, or unknown research chemicals that are potentially dangerous.
i guarantee that if you get a test kit, you will be able to score some legit stuff. once you get it, you will be set for the whole time. i cant emphasize how important having a kit these days is. even at more legit festivals and parties, nowadays around 80% of the "molly" is not MDMA. most of it is methylone, butylone and other research chemicals. some is meth, and some is bunk.
i am going to go ahead and say since its your first time you should probably only roll one of the nights. since you have tripped before you should probably try to find some doses or a 2C and just trip one of the days. you can wake up the next day after tripping and feel fine--not so much after taking ecstasy. if you take it two days in a row, not only is it harder to roll the second day, the effects are greatly diminished and the comedown is awful. most people become extremely depressed and anxious for about a week or so after rolling all weekend. it isnt particularly good for your brain, taking ecstasy in moderation is doable though.
if for some stupid reason you guys dont get test kits, try to find a group like dancesafe or the bunk police (i am not sure if they will be at EDC or GG, but definitely try and find them). these are harm reduction groups who set up at festivals and sell test kits and will test your drugs for free. they have kits that can tests for ecstasy, LSD, meth, coke, DMT, and lots of research chemicals.
either way i hope you guys have fun, i am sure if you end up getting the real deal you will have an amazing time!