For quick Mandates, you can use Bhim App. It is the best for Ipos. Within 10 mins you get the Mandate notification. They have a separate tab for IPOs. Google pay is worst for mandates. Firstly you dont get notified. Plus u have go into settings, pending mandates to check whether you have received mandate or not. Plus even after accepting mandate, There is a good chance of mandate failure.
One last thing. Always apply on 1st or 2nd day if applying through UPI. In case you dont receive mandate, u can cancel application through broker App and apply Again.
Jai Jinendra.....Ipo bharo aur bharne Do....