Market Condition: Ask is Specific Amount Below First Open of The Day

I wonder if anyone could help me with a simple way (Thinkscript in Thinkorswim) for my market condition to start a stock buy order when the Ask price is less than or equal to the very first Open of the day (first aggregation period, not the Open for the day) by a certain amount. For instance, -.011 below that first Open? I have used the DailyOpen study, but if I put in my buy orders to start at 9:30am when the market opens, it seems the Open price for the day is not always established, therefore I get fills at a price above the Open for the day. I would like to be more precise and make my market condition trigger in reference to the very FIRST Open price of the first aggregation period. I have tried using the First(); function in a study, but the market condition will not allow me to use my study (obviously because I must be missing something). Thanks!