Coffee grounds good for acidity, which blueberries like. I would mulch mine with pine shavings from the hamster store once a year for an extra kick, then I did mostly nitrogen (organic chicken manure) in the spring (leaves coming out) and fall (leaves falling off), and a citrus mix (this one, should be available at your local garden store). I believe it has a micro-nutrient supplement, but honestly, if you’ve got your blueberries in ground and with a decently acidic pH, this is totally unnecessary. The same brand has a berry mix, but whatever, its a more balanced feed with micros. Blood and bone mix would do pretty much the same thing, and apply that during/ before flowering (timing depends if you are high bush or low bush/ early or late). The biggest thing I learned about blueberries in the time I was growing them was how much they LOVED being trimmed. Mine responded very well to trimming and would pump the years after a trim.

My fertilization schedules are always centered around life stages. Nitrogen for new leaves/ branching; micronutrients (and maybe sulpher) for flowering/ fruiting. I’m basic af.