Hi Eduardo,
Glad to hear Rituximab has been working well for you. Especially good to hear you're coming off the pred quickly. I've been on pred for many years and the side effects are bad.
As for remission, no one can tell how long. Some people can only achieve remission whilst on drugs such as pred, others can be drug free and if really lucky never relapse. I don't think the method in which you achieve remission (rtx vs ctx vs mtx etc) has an effect on how long remission is likely to last, but there is research into which method/treatment is best for maintaining remission (daily tablets such as azathioprine vs occasional infusions of rtx, etc)

I wish you well in your remission and hope it lasts a very long time!