You should always use an after-shampoo conditioner whatever your hair type. Pour a small quantity into the palm of your hand, rub your hands together and smooth the conditioner over the hair, paying particular attention to the ends. Do not rub into the scalp or put the conditioner on the hair near the scalp. Rinse immediately.

There is no reason to leave conditioner in your hair for any length of time. A well-formulated conditioner should act on the hair immediately.

You can’t 'over condition'. If you think you are - you may be using the wrong conditioner, or too much or not using it correctly.