Around 10 months is a okay time to start slowly introducing dairy into the diet, but not to replace formula. I was advised to try yogurt around this age with breakfast along with cheese in the baby's food and other dairy products. When it is time to change to whole milk, to start with 3 parts formula and 1 part milk, then after a week, use 2 parts formula and two parts milk, and so on until the child is drinking whole milk full time. Another way is to start with one cup of milk a day with the rest being formula, then add a cup of milk while removing a cup of formula each day until the child is drinking only milk.
If you are going to start weaning off of formula before age 12 months, please do so under the assistance of a pediatrician. (Problems can arise, including allergies that may take years to grow out of.) Otherwise, please wait until age 12 months. Children do not need tea until much later in life. If you want to have the baby drink something other than formula, water is just fine after 6 months and you can add juice sparingly. (unless juiced yourself, once every other day or so is fine although some would say every day is okay as long as it is less than 6 ounces. I personally could not do that until later on and it was 3 parts water 1 part juice. Also make sure the juice is from a cup.)