Marinating chicken takes between 30 minutes to 12 hours depending on your preferences for the chicken and it's flavor.
When marinating chicken to enhance the flavor of the chicken you're cooking it's recommended to marinate the chicken for around 12 hours.
Some people marinate their chicken for only 30 minutes to 60 minutes which is good enough for some people but if you want the best flavor it's best to allow the chicken to marinate for at least 12 hours.
I always marinate my chicken for 12 hours and since I've started marinating the chicken for 12 hours instead of 30 minutes the flavor of the chicken is much better.
Chicken doesn't need marinating though to tenderize it but marinating the chicken does help with the flavor and you'll have a much better tasting chicken when you do marinate it before cooking it.