[FrostZ]

Since you have a new thermostat on the way I'd wait till after the install as you’ll be introducing a bunch of air by popping off the T-Stat housing. First I’d make sure both the top and bottom of the main coolant reservoir are filled to their proper levels once the car is back together, then with the engine running crank the heat to allow coolant to circulate in the heater core and allow the engine to warm up to open the T-Stat. Once up to temp you can hold the engine at varying RPMs to try and purge any air out that you can and refill as necessary. There are vacuum tools you can buy or have done at a shop to get every little bit of air out but that’s what the reservoir is for over time. Hope this helps!