After this time, turn the chicken - it should brown nicely - if it doesn't, increase the flame.
On the other side, leave it for 15 minutes on medium heat and another 10 minutes on low heat. After this time, try the chicken, prick it with a knife or fork and see that no more pink sauce flows from it.
If it is not done, leave it for about 15 minutes on medium heat on one side and on the other.