Thank you all for your responses. I went to see the rheumatologist today and turns out my over achiever of a doctor had already contacted my insurance to verify what medicines they would cover.
Today they taught me how to give myself Humira injections. Here's to hoping it helps me.

I will have Cigna Plan G as a supplement

A lot will depend on what Medicare you are on. Part d? Supplemental?

I will be on MC and a supplement after the first of the year, does anyone know how they pay for biologics? I'm a little nervous about the cost...

It all depends on your insurance. It could just be a small co-pay to a large deductible. Mine has varied over the years with the different insurance policies. From $40 co-pay to a $1500 deductible then $300/infusion. There is no standard answer for you. The best thing is to check directly to your insurance company and ask specifically what the coverage is for you the specific drug your rheumy wants you to take. Some of the injections are under prescription coverage while the infusions are under medical (simlar to chemotherapy)