Well, personally, whenever I plant a new shrub, tree, whatever, I give it the recommended dose of seaweed fertiliser, Seasol usually. I understand this acts as a root hormone, get's the roots out and established into the new soil as guickly as possible, and also helps overcome the shock of transplantation. As for whether you put slow release fertiliser on top or dug in a little, I guess dug in a little would be best.