Congratulations, you have taken the plunge to give your first BJJ class a try! You have done all the research, found a local gym. The only thing left to do is figure out what to wear to your first BJJ class.
Hopefully your soon to be new home would have told you what to turn up in, but just in case, here are some pointers with what to bring and wear.
What to wear:

On top:
Bring a sports tee shirtWear a short sleeve t-shirt or one of those dry-fit running shirts if you have one. You will get sweaty so just be prepared for it to get a little bit soaked.
For women a sports bra is a must for grapplingFor women, also wear a sports bra if you have one.
On the bottom:
Bring shorts without pocketsWear shorts without pockets if you have them. This is to stop any fingers getting caught in them. Think, basketball or running shorts.
What will be supplied (probably):
You will generally be supplied a loan BJJ GiIt’s likely that your gym will give you the loan of a Gi for your first class, so you can just put that over your shorts and t-shirt, but if they don’t then the shorts and t-shirt will be enough to get you through your first class.
What else to bring.

It’s a good idea to bring a towel so you can dry off sporadically throughout the class.

Bring a bottle of water too, you are going to work up a sweat and loose some fluid so it’s best to keep topped up.

Bring thongs, flip flops, Jandals, Havana’s, sandals or whatever you call them where you come from. This is because you are going to be bare footed on the mats while you train, but if you want to go to the toilet before/during class you are going to need something on your feet. No-one wants to train with the person who walks from the toilet in bare feet onto the mats.

A bag. You have now got a lot of stuff to cart around. Probably best to bring a bag with you.
The most important thing to bring!
Is a positive attitude.
Leave your ego at the door and come in with an open mind. If this is your first time grappling with someone it’s going to feel foreign and maybe a bit invasive. Everyone on the mat has been where you are and is going to be more than willing to help you learn the ropes.
Remember: A black belt is just a white belt who never quit.