I've learned that Crohn's is different for everyone. My "mild" case resulted in a stricture and then a resection that took out about
20cm of small intestine.
Never under estimate your crohn's! Too many times I thought I was doing well and my blood tests showed otherwise.
I've realized you have to maintain a “Constant vigilance” (Alastor "Mad Eye" Moody from HP) when living with Crohn's.
To answer your question though... my symptoms before diagnosis were diareah, and vomiting. I had no pain until after diagnosis when my strictures were becoming so severe.