Planting blueberry bushes

I currently have 3 blueberry bushes in pots, but now have a space in a bed against a fence that would like to move them to. How should I go about this, I know they want ericaceous soil so what’s the best way to do this?
should I dig out the bed and replace with ericaceous compost, if so how deep should I go?
or is there a better way like treating the soil?
Thanks in advance