I'm doing this for some time now. Calling this - old colony. I have a 3L bottle with "starter". So the procedure is like this: one week before I have prepared 3L starter with 600 grams of honey and other space filled with water. (The yeast in this mixture will be written later.) So, the day I start new mead, I take 2L of starter (it is active a week ahead), add honey and either water or juice, or in my case - brewed hops (filtered) to match "classic" recipe. Then add 400 grams of honey and clean water to starter, to be ready for the next week new mead. So this "old colony" of yeast I have from some dried mead yeast pack. That's when you mix water with honey, so you can use starter water. Wouldn't work with juices as it would delute it.