How long does it take MS medcine Rebif to work?

On Nov 2 I starting taking Rebif for my MS. I started at 8 mcg. Now taking 22 mcg and will go to 44 mcg in 2 weeks. I have a lot of trouble walking. I had read that it might take 3 months or longer for effect. Anyone else taking Rebif or know how long before I might see improvement?