Sometimes foods will affect me within 1-2 hours of consuming it, but other times its the next day or two. I think it depends on what it is. For example, I cheat once in awhile and have some marinera sauce and I will generally feel it within a hour or two. But recently I ate a beef hotdog (I no longer eat red meat) and I felt bad for about 2 days afterwards (not the day I ate it though). I would suggest you keep a food diary and keep notes on how foods effect you, and avoid those that cause problems. Within time you will learn what you can and cannot eat. Its pretty individual for most of us.
Flares yes should be somewhat comparable to how you felt before meds. When I have been in remission and things start acting up, I usually allow myself at least one week and if things don't get better then I know its time for stronger meds and that it is a Crohns flare and not just a few bad days. You will have bad days every once in awhile that really aren't flares per say, but usually the result of an increase of stress or bad foods.
Alot of people don't realize either that anxiety can develop because of Crohns. You start worrying about all the what if's that can happen with this darn disease etc and this anxiety can cause gastric issues such as diarrhea or nausea. I just discovered this about 2 years ago, and now have Xanax (lowest dose) available when those times hits and I am able to stop it right away with the help of this med. I haven't had one of those bad 3-5 days in bed times since I have recognized the anxiety. JMHO
Hope that helps.
Gail*Nanners* Co-Moderator for Crohns Disease and Anxiety/Panic Forum
Been living with Crohn's Disease for 33 years. Currently on Asacol, Prilosec, Estrace, Prinivil, Diltiazem, Percoset prn for pain, Zofran, Phenergan, Probiotics, Calcium w/Vit D, and Xanax as needed for my anxiety. Resections in 2002 and 2005. Also diagnosed with Fibromyalgia, Osteoarthritis, and Anxiety. Currently my Crohns is in remission, but my joints are going crazy!
*Every tomorrow has two handles. We can take hold of it by the handle of anxiety, or by the handle of faith"*