One way to control the flavour, making it more mild, is to create a runny sponge a few days before hand. I usually keep my starter extra-thick and then create a runny sponge from it (using by volume 1 part starter, 1 part flour, and 2 parts water). Feed it at least once a day for at least 2 days, twice for a more mild texture, don't worry if you make too much, the extra sponge can become sourdough crackers or bread. By having the sponge runny and at room temperature for a few days before baking day helps make the bread more lofty and less sour.
A word about Sponge. Although the word sponge can mean different things in various parts of the word, I use it here to mean a fairly active runny batter like substance made of sourdough starter, flour and water. Make the sponge at least 4 hours before you plan to begin the bread.