How long from eating until that meal is defacated?

It varies. Some individuals have a very rapid and pronounced gastrocolic reflex (the reflex that stimulates your colon to begin defecation after your stomach has encountered a meal), while others have less efficient reflexes. In my opinion, the gastrocolic reflex of some individuals is effectively useless, as it does not stimulate the bowel sufficiently to trigger a bowel movement anywhere near the time of a meal.

Keep in mind that the normal range for bowel movement frequency is anywhere between three times a day to once ever three weeks.

A BOWEL MOVEMENT ONCE IN THREE WEEKS IS NOT NORMAL. IT IS CONSTIPATION. IN YOUR DAILY LIFE OF HABIT (E.G. NOT TRAVELING), ONE SHOULD BE POOPING NO LESS THAN ONCE A DAY.