Creating a recurring plan with a future start date can only be done with Virtual Terminal.
Given that recurring plans with future start dates can only be created in Virtual Terminal, you likely want to start by making sure that Virtual Terminal is enabled. To do so, click on your organization's name (usually located on the top right), click into Settings, and click on Virtual Terminal in the left-hand menu. If Virtual Terminal is not already enabled, you can do so by clicking the Enable Virtual Terminal button.
Once your Virtual Terminal is enabled, you can utilize it to create a recurring plan with a future date. The green Virtual Terminal button is available on both the Donations and Recurring Plan tabs, or by pressing the T key on any screen of your account. This will launch a checkout form with all the necessary fields to complete one-time or recurring donations.
Within Virtual Terminal checkout, when donation type is set to Recurring and the payment option chosen allows a future start date, you will have the option of selecting a "Starting on" date, letting you set it to start either today or any date in the future.
For additional information on utilizing the Virtual Terminal please visit Using Virtual Terminal to process Donations.