How's your heater working?
If it blows really hot air, then it might not be an air pocket. If there is no heat when you turn the heater on that might be a trapped air blocking the proper circulation of coolant.
When i change the coolant I refill new coolant very slowly (it's hard to do) and once it is filled then i start driving few blocks with heater on fool blast carrying some of coolant with me.
Usually i notice that there is no hot air for a while then it start to blow out hot air at certain point. I stop my car at that point and refill more coolant. This worked all the time.
