Trying to use Blue Devil head gasket repair, do I need to remove both thermostats?

So, should I put back on the thermostat housing and water control valve housing without the thermostat and water control valve and then add the blue devil and crank my car?

Okay, I removed both thermostats & put both thermostat housings back on, put the Blue Devil Head Gasket Sealer in the radiator and topped it off with the proper 50/50 engine coolant/Antifreeze. Then I cranked the car, turned the heat all the way on and let it run for 35-45 minutes (until the temperature started going up and the coolant in the coolant reservoir was bubbling up out of the spout on the side of the tank) Should I install both of the new thermostats and gaskets then put the thermostat housings back and add more Head gasket Sealer and Coolant and crank it with the heat all the way on again? Or should I just install the new thermostats, put the housings back, fill the car with Coolant/Antifreeze and then crank it to see what happens?
Thanks