Here's how you can do that:
Dashboard --> Goal in which you'd like to setup the SIP --> Invest --> Start SIP --> Fill up the amount, duration, risk level etc. --> Review and Confirm SIP.
Please note that you would be able to setup an SIP from your dashboard up to 1 day prior to the scheduled SIP start date. For example, if the scheduled SIP start date is January 7, you can setup the SIP till midnight on January 6.