Unless there's a heater control valve within the heater hose line, your course of action is not needed. Coolant flows through the core at all times on many cars using blend doors for heat.After doing a coolant flush and change, I like to drive around with the heat on high to get circulation in the heater core. Fan is on the lowest speed to make driving tolerable, but is there any chance of damaging something? Like something in the dash or air ducts that would get too hot? It's only 50° more than when it's 40° out and you turn on the heat, so maybe not an issue?