One way you can do is to check your data subscription on data management page and see you have subscribed to the real time data or not. Other way is to compare a moving stock with the quote that you get through YAHOO Finance and see they are the same or not. Yahoo finance gives you real time data but you need to refresh the page (I believe)now I don't know if my stock quotes are delayed like they use to be or have been upgraded to real time in the basic futures and forex package. How would I ever know? I never trade stocks with ib and have no stock quotes on my screen.
I use to keep some stocks I own at other brokerages at the bottom of my screen, and check them when times were slow. But I have enough going on in my trading to also be watching what is going on over there in buy and hold, so I deleted them.
But how would I know if my spy quote is real or delayed? I guess I'd have to watch it and wait for a move in the futures.