I saw improvement very quickly too. I think the biggest problem for me was grains. For about two years before going primal I was already eating gluten-free, but even though that did help my digestive problems continued to plague me, with bloating being one of the more annoying symptoms. Once I eliminated grains altogether I was amazed at how much that helped. Within just a couple of weeks I could see definite improvement in my symptoms. I think my system is still in process of healing because I still don't feel 100% normal every day, but I find that the stricter I am about eating primally and avoiding the trouble makers the less frequently my symptoms return. It's definitely a huge incentive to stay on track!
We must learn to do what the leaf and the whale and the wind do of their own nature. We must learn to keep the balance. Having intelligence, we must not act in ignorance. Having choice, we must not act without responsibility
-Sparrowhawk, The Farthest Shore by Ursula K. LeGuin