If you mean Photo 9, hard to tell if that's a blueberry plant or not to me, the hairy leaves don't help. If that's what the suppliers packed them in then it could be just peat. Not very nutritious at all I don't think but ideal for blueberries and at the correct pH. With your potting mix and Miracle grow soil, I think you'd want to lower the pH rather than raise it. Don't know too much about coffee grounds for this purpose, sounds like a slow and probably adequate way but I think most here would use sulfur to the same effect or you could just buy a bag of peat. I'd have to recommend getting peat to plant them out as it's simpler and effective, amending soil is more for tuning the pH later and for larger scale plantings really :p I've also read that you should mix the peat about 1/2 and 1/2, your potting mix stuff might be fine for this or any soil without an alkaline component (i.e. avoid adding sand containing shells which are made of calcium or compost containing lime) which will raise the pH. If you are going to mix peat and soil to plant them in the ground, add some grass clippings and green matter that will break down over time. I put this in an 18" x 18" hole for my plants and they're quite happy several years on. Plant where there's adequate drainage, mulch to retain moisture and get a companion blueberry that flowers the same time for a better fruit set. Water only with rain water too though if you must you can attempt to lower the pH of tap water by adding vinegar.
There are a lot of threads about blueberries here to look through to get in to greater detail, the above might seem like a lot of info to take in too compared to what the Lowes guy said but it's basically some pointers about growing a plant that wouldn't like your garden soil much. Anyway, hope some of it helps and good luck with the plants.

Coffee doesn't make the soil more acid.

Thanks for all the help. I should of just bought some peat from the get go. The guy at store just told me to add coffee grounds and I would be fine. The more I read, the more I was better off with peat. I have 3 plants in 3 pots. I wish I didn't live in an apartment and could plant them in the ground and not pots. Where do you buy this sulfur and would it have the same effect as the peat?