Once your starter has reached its PEAK RISE, mix your leaven & let it do its magic! The time it takes for a leaven to rise and reach its peak vary. When a perfectly peaked reactivated starter is used to mix a leaven, the leaven will take a good 2-3 hours (more or less depending on the temp of the environment & how much starter is in the leaven) for the leaven to reach its PEAK and be ready to mix your dough!