SImon will answer it better, but the first and last 10 min of every trading day is opening and closing auction. During this time period the market "settles" in and if you look closely enough prices could swing quite high and low from closing price yesterday. The opening of the warrant market at 09h10 is to avoid (protect?) warrant traders from these price swings that in fact might take you out on a stop without your intent.
Also I understand that the underlying vs the matrix price (buy/sell) must be in place for 30 seconds as the screen refreshes every 30 sec on their side. I have on many an occasion queried why my trades were not effected and they missed the on screen as the price change in 30 sec was over before they see my trade. Irritating but thats the way it works. so in the first 10 min of market open the prices change so often these levels could easily be missed....this is what i have figured so far in my trading.
So you can place order in the first 10 min but it will only be effected after 09h10. I usually wait till after this period to make a trade decision anyway..IMO