I like your flush plan. I would be really surprised if something were dislodged and causded serious problems though.
For your oil change purposes, it will help tremendously, to have the engine blazing hot, I have read that it takes an average of 18 miles to reach full operating temperature. My experience seems to bear that out. The temp guage will get to operating temperature fast, but it takes a while for the rest of the engine to reach it. In driving cars with oil temperature guages, I have seen the oil temperature lag the coolant temperature by quite a bit of time. From these unscientific experiments I have seen that it takes about 18 miles for oil temperature to stabilize.
Whether you change it yourself, or take it to Jiffy Lube, your mission will be much better accomplished by pulling the plug with the engine at full operating temperature.
Change oil hot and change oil often,
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in