Welcome to the group.
It is best to be prepared for your appointment by arming yourself with a written diary of your symptoms (Which joints are painful or swollen or red or warm. How long your joints are still in the morning. Other symptoms you may have - fatigue, etc). There are even apps to keep track. You should have a list of whatever medications you have tried, how long you tried them, and if they worked. A list of any questions you have.
You will likely get at least blood tests (though negative blood work doesn't mean you don't have RA), and possibly X-rays. Other tests may be an MRI or ultrasound.
Some rheums will give you a trial of some medication to see if it helps or not while waiting for labs, some may wait, and some may discuss RA meds with you.
Read about the different types of meds -- DMARDS and biologics -- some people are on one or the other and some are on both.
Medications for RA are the best treatments, and should be started early to have the best chance of reducing risk for long term joint damage and deformity and to reduce the risk of other RA complications.
Bring a trusted family member or friend to help be a listener since you may not remember a lot of what is said.
Ask for written material, and how to contact the rheum with any questions or issues you may have.
Bring your patience. Not only can diagnosis take a long time, but medications can too.

Good luck and let us know how it goes.

Hi, Groessler. I went into my first appointment with a rheumatologist thinking "this is the day it will all turn around', and it was a real psychological hit for me when that turned out not to be the case. At last, it wasn't in any immediate sense. This part is so terribly frustrating, but it seems that nearly without exception it takes some time to get the RA under control. Medical protocols and insurance regulations seem to demand that meds be prescribed in a certain order, and you need some time to see if one works before making a switch. Just remind yourself that you don't want to over-medicate, so trying out the 'lesser' approaches first does make sense.

Doodlebug gave you great advice so I won't repeat any of that, but it was, as usual, spot on.

Oh, just thought of something I meant to add. This is irrelevant if you are young, or if you've already had a vaccine for shingles. But if you're over fifty and haven't yet been vaccinated, please discuss that with your doctor. Here's why: the normal progression of prescriptions seems to start with Plaquenil, and after a few months, adding methotrexate, and then a bit later, trying a biologic like Humira. You cannot receive the shingles vaccine while you are taking Humira; in fact, you need to wait a few weeks after the vaccination before you can take any biologic. I did not discover this until, literally, two days after I started on Humira. i could have easily have had the vaccine during the six months of treatment before the Humira was prescribed.

I may have some details wrong in what I've written above, because I'm not a doctor. Perhaps there's a biologic which does not preclude the vaccine; I'd have no way of knowing that. I'm just suggesting that you ask your doctor, because you may be able to take care of that now.

Groessler - Depends on the doctor, what symptoms you are having, how much pain you are in and what tests were already done that led you to be referred to a rheumatologist.

But do expect blood tests to diagnose or confirm the diagnosis.