I always do my exercises in the evening after dinner, but I dont know how long I must wait after eat to my exercise routine?

It just depends on your tummy. I have to wait 1/2 an hour but everyone is different.

When I'm well restricted, I find I need at least 2 hours between the end of my meal and the time I start to exercise. Any less time than that and I feel uncomfortable.

So I think it's pretty individual. I can tell when I'm okay to exercise again just from how I feel.

With my cast Iron gut I can eat my dinner and head straight out the door to run.

The only things that give me trouble when I do this is if I've had a lot of Fluid - or Soup. It sloshes and that's revolting.