Ahh, no worries.
I would use the bleed bolt when you think the thermostat is open whilst it is running. Don't undo it all the way, just enough for a good amount of flow for a few seconds should be enough. Bit messy lol but...........
I also usually leave my header tank cap off aswell until 2 fan cycles have completed whilst also squezzeing that hose.
Also of note, is your heater control on max??