@The Joker bhai, selling pressure is likely to be there.
Even if we assume that none of the QIBs will sell, still HNI + Retail is approx 50% of the issue, means about 12.5% of overall market cap.
If it lists at 30%+ premium, good chunk of this 50% can be expected to exit at least partially, if not complete exit. So, in my opinion, avoiding pre-open buy orders is advisable.
Anyhow, as a rule, I never put pre open orders, neither buy nor sell. I am sorry, but I cannot advise what I never do.