2000 4-cyl Engine won't heat up replaced thermostat!

The car doesn't have any heat output. The gauge won't budge. Car runs great. Changed thermostat. The cooling fans seem to be OK. Fluid level is OK. It would be nice to have some heat here in Iowa. Thanks! :-)

Use a Prestone flush kit to force out any air pockets.
If there's an air pocket near the thermostat, the heated coolant cannot open.

Can I just take out the thermostat and wait until it gets warmer outside to flush it?