I suppose every GI does EEN and maintenance meds a little differently depending on the case. When my son was dx'd we were given the choice of Prednisone or EEN. We ended up going the Prednisone route, but had we chosen EEN, our GI would have put him on it for 3 mos with a NG tube, and no solid food. The maintenance med would have been started right away as it can take weeks/months for it to kick in. Imuran/aza takes about 3 months (I suppose 6mp is much the same), and those are often the first drugs of choice if your GI tends to use the "step-up" approach. My son was not able to tolerate Imuran, so we switched to Methotrexate injections, which kicks in a little sooner-around 6-8 weeks. Your GI may use a "top down" approach, starting with a biologic med, like Remicade or Humira. I do not have any experience with the biologics, but I believe they reach therapuetic levels rather quickly. Best of luck, and take care!