My GI told me that it does not take 3-6 months to kick in unless you start at a very small dose and work your way up to it. (just repeating what I was told about azathioprine, which I believe is close to 6mp).
I started azathioprine/cipro/hydrocortisone e's at the same time and in a couple of weeks I had great improvement........don't know which is responsible, but I have since stopped the e's.
IMO - (based on thinking the anitbiotic is not a maintenance drug) We all need to be on some kind maintenance drug to reduce flares and symptoms. I would be leery of reducing or discontinuning the 6MP, since she is doing well or at least give her some more time of feeling well before changing, it would be terrible for her if she went through another flare again so soon.
I know some do not agree w/me, but that is my 2 cents.