For IPO you need to understand that the technical data is not available. So after allotment, if you ask what should I do, shares are falling, we can’t help as there is no strategy available to bail you out. We don’t have a magic wand to tell you what will happen if the data is unavailable.
So, even before applying for the IPO, you should be clear about what you would be doing?
1. Investing in the IPO for long term - Check the sheets from the above link
2. Selling them on listing day, for gains
If you ask after getting the allotment, and share falling, there is nothing that can be done in this regard.