By default, when enrolling prospects to an automation, they start with the selected step as soon as possible. However, you can choose to start later.
To do so, you need to use a Delay step. Just add this step at the beginning of your automation (on the 1-st place) and set the needed delay time (up to 30 days).
Then, when enrolling prospects into this automation, select the delay step. They will stay in this step for the selected period of time and then proceed to your email step.