Methotextrate and burning muscle pain, stiffness

I am newly diagnosed with RA.  I have been prescribed Methotextrate, 4 tabs once a week.  I have only taken 2 dosages so far, no relief yet.  My question is how soon before I start to feel some relief?  Also, does RA cause burning muscle pain.  I have constant muscle stiffness all over my body, and sometimes the muscle feel as if they are inflamed.  The doctor doesn't think i have fibroymyalgia because I don't have deep muscle pain when touched.  My muscle pain is more stiffness all over, and the feeling that the muscles are inflamed.