I need to flip some today to avg this down, where

I need to flip some today to avg this down, where do I set my sell order? I have over 1/2 mil shares and I am selling less than 100K. Where do I set my limit price, or should I use a market order? I am not much of a flip guy, but I have no choice today. Anyone that is good at this sort of thing. feel free to chime in. The rest I am holding he*% or high water!