Best shop practice:
Marinate TC drain plug overnight with penetrating oil of your preference.
Dig crud, if any, out of drain plug hex hole to allow full insertion of hex tool. Not doing this may result in stripped drain plug.
After TC drain plug removal, insert small, hollow, plastic swizzle stick-straw in drain hole to break vacuum and allow fluid to drain overnight.
Didn't notice your engine. According to MB OM651 crankshaft must be turned in correct direction or risk derailing cam chain. Out of abundance of caution, apply same practice to other engines.