Yes it's OK to brown chicken the night before and then finish cooking the chicken and preparing the meal the next day.
I will sometimes brown chicken the night before myself when I'm really busy and need to get the food cooked and ready for the next day especially if I'm having company over.
Browning the chicken the night before allows more time to get the rest of the food prepared.
Just be sure to place the browned chicken into the refrigerator as soon as you can after browning it and then thaw it out the next morning.
You can reheat the browned chicken in the oven or place it in a pan and reheat it some the next day.