DLA to PIP

I probably already know the answer to this but figured I'd check to see if I was right. In the scenario where you are moving from middle rate care and higher mobility on DLA to enhanced care and enhanced mobility, as there is a financial increase, do you get the difference backdated to your PIP claim date? Orr do they just pay you the PIP rates from the first payment after the decision is made?

Thanks Gordon, I was right then! Tight bar stewards they are!