Sounds as though your thermostat is stuck open.
All thermostats have a design temperature they are supposed to maintain by opening and closing to control coolant flow through the radiator.
At start up, the thermostat should be closed, blocking flow to the radiator to allow the coolant to warm rapidly up to design temperature, at which point the thermostat starts to open to allow the coolant temperature to be regulated by flowing through the radiator.
If the thermostat is stuck open, the coolant will take a long time to warm up and will probably not get up to temperature in the winter unless in slow traffic with poor airflow through the radiator.
Stat needs replacing, mine dropped from approx centre gauge to quarter. If I wanted heat in the cabin it dropped further and also took an age just to get warm.