I often place MOO and LOO orders for NYSE stocks though IB. I specify OPG, SMART routing, and not extended hours. I have never tried submitting the order the previous day. I always get execution at the NYSE open. Quite often the open is different from the open price shown by the quote vendors. I can tell I am getting the NYSE open by watching the action unfold. The NYSE open usually has high volume and is the beginning of active trading.