Stir the mixture every 12 hours. Start taste-testing the syrup at the 48 hour mark. Exactly when it's "ready" is subjective and will also change based on indoor temperatures and the activity of resident microbes in the mix. Our sparkling elderberry syrup is usually perfect for us at the end of day 5-7, but your preferences may be different.
Sparkling elderflower cordial https://www.tyrantfarms.com/how-to-make-sparkling-elderflower-syrup/