Postman has many built in Javascript libraries. Moment is one of the more useful ones for getting dates such as today’s date or tomorrow’s.

Creating a Date with Moment

Moment is another tool build into postman that can be used for your test. This is great for creating a rolling future, current or past date. You can add and subtract time be it minutes, hours, days, months, or years. You can also change the format to match what you need.

var moment = require('moment');

var date = moment().add(10, 'days').format('MM/DD/YYYY');
var date2 = moment().add(1, 'month').format('MM/DD/YYYY');
pm.environment.set("date", date);

Links

Postman Quick Reference Guide
Chai Assertion Library
Regex Cheat Sheet
Postman: The Complete Guide on Udemy