As I have stated earlier, our digestive fire is directly related to The Sun. Here I will tell you why. The Sun is energy source to the earth and it is a known fact that plants make their food using sunlight. Sunlight itself is a cure to many diseases given it is filtered properly by ozone layer (without uv radiations); it isn't for nothing that regular sunbathe are considered to increase immunity.
Our body contains some chemicals which when secreted activate particular glands. It is found that the chemicals needed to activate the digestive system are secreted in our body when the sun rises in the morning and reaches the optimum level after 2-3 hours of rising from horizon. It is said that anything that is eaten at that time gets digested perfectly. When the sun is directly overhead (noontime), the secretion is limited and the digestive system is moderately active. In the evening, before sunset, the digestive system less active and it becomes inactive for the food right after sunset. The only thing that is recommended after sunset is milk, as the juices secreted by our stomach at night are useful only for the digestion of milk.
Therefore everything edible has a time associated with its consumption. This post is only for the drinks and hence what to drink and when is as follows:
7 am -12 am : It is the right time to drink fruit juices. One can have a glass of fruit juice right after or with the breakfast.
12 am-6 pm : It is the right time to have yoghurt, buttermilk or any fermented drink. You can have it right after the lunch if thirsty.
6 pm-12 am : It is the right time to drink milk.
NOTE: One should drink water only before and after 50 minutes of their meal.