I've never submitted an option limit order outside trading hours for possible execution the next day. Sometimes iron condors or back ratio spreads take a bit of time to setup and I would prefer to do this in the evening when I have more time to study it. I can use the Black Scholes option pricing model (current IV of the option chain at the expiration I want to use) to estimate the price for the combo or use historical last close data for each leg. I'm selling far enough out in time and OTM that the combos that I hold usually don't change drastically day to day (when I open, they have close to 0 delta and I try to collect a small credit). I think my broker will also let me submit a conditional execution based on the price of the underlying. My question is if I set an aggressive entry, say I take the last combo price and then discount it aggressively, say the combo last traded for 2.50 and if I enter a limit of 1.50, if the underlying opens up at the same price as it closed and if very little changed, will I get a fill close to 2.50 or would I get a crap fill closer to my limit..assume S&P500 stock or popular ETF? If so, would be nice if there was an order algorithm that let me enter 2.50 as my limit and then drop the price 0.05 every minute until it hits 2.30...I could do that via the API, but not sure it's necessary.