Welcome to HealthcareMagic.
The timing of defecation is more of a trained and controlled reflex.It is a habitual process.I would advise you to altered your diet schedule , add more of fluids in your diet , drink lots of water , and make a habit of defecation at a certain time.This can relieve constipation
if it is habitual.The point here is , constipation either voluntary or involuntary , causes increased absorption of water in intestine and make s the stools hard.Hard stools inturn cause constipation.The cycle continues.The only way to break this cycle is by using laxatives like Lactulose
or stool softeners , drinking plenty of fluids to change the consistency of stools.
If none of these work , you should get evaluated for piles or malabsorption
syndromes or bowel disorders.
Hope this information helps you and others.