@Rky The IPO window for HNI clients (both bHNI and sHNI) closes at 3 PM on the last day of bidding if using ASBA mode. Why take any chance even if some bank allow some extra chance. Consider the cut-off time for bidding as 3 pm only. However, for sHNI, if bidding is done through UPI mode (UPI is accepted upto 5 L), cut-off time is 5 pm to accept the mandate. Ideally, the applications should be completed within 1 pm by individuals as a safe guard towards last minute glitches.
Hope, it helps.