Take your tea on an empty stomach if your purpose is cleansing, detox or the relief of symptoms; and if your tea is for energy, stamina, vitality or nutrition, it is best to have it with meals.
Herbal tea is versatile. You can drink it hot or warm. so comforting on a cold day. You can let it sit and steep in the pot all day if you want, and just strain the concentrated cold tea and top it up with more hot water. Or put it in the fridge and chill it for a glass of iced tea - add a lemon or lime slice - mmmm!