some follow up questions, is this made up of rye flour?
No, white bread flour
And how do you use the starter that you already have? Do you add that in later, or are you just working from this amount you've made the day before?
You can then refresh the starter you already have, leave it outside a few hours then back in the fridge. With leftover starter that you'd bin you make delicious crumpets or a spring onion pancake for breakfast :)