I tried to place stop order on IB but I got this message that your order will not execute till 8.30 AM is there some settings or I cannot place stop order in after hours? thanks
Either take a look at your Order Ticket, tab "TIF" or use the "configure" menu to configure your order defaults to allow execution outside of RTH.
make sure that you checked (configuration -> order): "allow order to be activated etc. outside of regular trading hours"