Turning your heat pump up to say 28°C will not make the room warm up any faster. In fact, it will use more energy as the heat pump attempts to absorb energy to achieve this unrealistic temperature. If you set the temperature to what you want, say 18-22°C in heating mode (which is a comfortable temperature during winter), the heat pump will respond in the most efficient way to reach this  temperature quickly and maintain it. You can use a timer to activate the temperature half an hour before you arrive home, so your home is warm and cosy when you get there.