I have tried a lot of fertilizers for Blueberries, but this is definitely one of the best. I like to use it by mixing it right into the soil (it can be applied by top dressing too). The best time to apply would be early spring. 

 

Look at how good mine look! Also, after they are planted, it's good to use pine bark chips to cover them. This is much better than mulch or stone. Using multiple varieties of bushes will often aid in pollination, which in turn produces more berries.