You have the ability to set custom timeframes for when automated messages and abandoned cart reminders are sent. You can select from one of the predefined options (e.g 30 Days or 45 Days) or you can use the 'Custom' option to set your own desired value. Tip: This can be particularly useful when it comes to setting the Re-order Prompt Message timeframe. You should use the Merchant Analytics to discover the Average Reorder Gap and then set the Reorder Prompt timeframe to accurate reflect this.
How to Set a Custom Timeframe
On the automated message in question, select the 'Send After' dropdown and select 'Custom' at the top of this list.
Use the toggle option to set the desired amount of days.