The IV steroids are to treat an existing exacerbation. So you should experience a reduction in symptoms with the steroids.

The injectible, disease-modifying drugs (Copaxone, Rebif, Avonex, and Betaseron) are supposed to slow the progression of the disease. Their effectiveness can be manifested two ways: fewer lesions on subsequent MRIs and fewer relapses...

If you choose to take the shots, then you continue them until you find they are no longer working for you, you or your doctor want to switch because of side effects, or you want to try something new (which will hopefully be a wonderful oral medication that is proven far more effective than existing therapies and with no harmful side effects - fingers crossed!)

I have been on Copaxone w/ no side effects for over 8 months, so how would I tell iF it's working? On my next MRI? Thank you ALL!

Its difficult to tell for sure if your DMD is working. A good sign is if you remain stable with no attacks. A followup MRI is also helpful. I don't know how long a time has to pass before a followup MRI should be done. In my case I didn't have any exacerbations while on Avonex. This was preceded by several pretty severe ones. I also had a followup MRI which showed no new lesions. This was only done several years ago, and I had already been on Avonex for over ten years. So it was pretty obvious in my case that Avonex was working.
A consultation with your neurologist should shed a lot more light on this.

GeminiAmy -

I, too, have started Copaxone recently. I've been on it for about 5 months or so. My MS specialist said that I'll do another MRI at 9 months to see if it's working and to see how I'm doing. The Copaxone people told me that it would take about 6 to 9 months for the drug to truly start working.

I started on Copaxone on July 16th and my next appointment with the dr is Jan 11th. I guess I will see what's next.