There are a variety of factors that are considered when pricing an IPO - including timing, demand, market conditions, and more. A company will issue an initial price range in their preliminary prospectus (also known as an S1), but may change that range - and therefore the ultimate offering price - based on the aforementioned conditions in the days leading up to their IPO.
Please note that your order confirmation will be based on the final IPO price and that your IOI is non-binding.