Today is day 19 and yesterday I made new batch for today and I saw a lot of expanding. I think that my yeast is ready to transform into the leaven. According to Oxford Dictionaries a leaven is a substance, typically yeast, that is added to dough to make it ferment and rise. Tomorrow I will make the leaven so I can bake on Monday. It has been a long journey so I can not wait to bake my bread!