Happy to be discarding the grapes at this point. They were beginning to gross me out.
Add 1 cup flour to form a thick paste.
Divide the starter between two canning jars, cover the jars with cheesecloth, and secure with the metal-ring bands. Put them back in a warm spot. If the starter triples in size within 4-6 hours, it is strong enough to make your bread rise.
If it doesn't, feed it each day with 1/4 cup each warm water and flour. If the jars get too full from feeding, discard some of the starter.
When the starter is strong enough, remove 1 cup to make bread.
So, now we wait...