To see if your t-stat is working properly, feel and squeeze the top radiator hose. If there's pressure while the engine is running warm, then coolant is flowing through it and it's opening properly. You may have just gotten a large air pocket come out. Try it again. Your temp gauge should also give you a clue as to whether or not there's a problem.
Personally, I find it easier to leave the bleeder screw on, and watch the flow back into the expansion tank. When you see a steady solid stream at around 2500rpm with the heat full on, you're good to go. If it's coming out in spurts, then you're not done yet.