Begin by pouring the warm water into a small glass bowl.
Sprinkle the yeast over the water and let it sit for 5-8 minutes to dissolve completely.
In a larger glass or plastic bowl (avoid using metal bowls or utensils), combine the flour and sugar, stirring with a wooden spoon.
Add the milk, then mix in the dissolved yeast mixture.
Cover the bowl loosely with plastic wrap and let it sit until bubbles begin to form.
Once bubbly, transfer the mixture to a gallon-sized zippered plastic bag and seal it. Leave it at room temperature (this is Day 1).
Day 2: Mash the bag.
Day 3: Mash the bag.
Day 4: Mash the bag.
Day 5: Mash the bag.
Day 6: Add 1 cup each of flour, sugar, and milk. Mash the bag thoroughly to combine.
Day 7: Mash the bag.
Day 8: Mash the bag.
Day 9: Mash the bag.
Day 10: Pour the starter into a non-metal bowl. Add ½ cup each of all-purpose flour, granulated sugar, and milk, and mix well using a wooden spoon.
Divide the starter into 1-cup portions and place each into separate zippered plastic bags. You should get about 4-5 bags.
Seal the bags and share the starter with friends along with the instructions. Keep one starter bag for yourself if you like. This will start again from Day 1.
Make sure to keep one starter bag for your own use if desired. Alternatively, you can freeze the remaining starter bags, and revive them later.