If you are going to age it for quite some time, dry can work, just takes a while for the flavors to start coming through with blueberry. If you want to drink it sometime soon, I'd at least make some of it off dry. I've done a few at 1.010 that I thought were too sweet, but my wife liked. I aimed for 1.005 on the last one and we both like it. I'd personally stay at 1.000 or higher, the sweetness helps the blueberry flavor come though, if lower I think it is a bit bland (unless aged a decent amount of time, like 18 to 24 months). You need to decide what you like. Just remember if you back sweeten it, as it ages the perceived sweetness level seems to increase a bit (ie. aim a bit low, get it to where you say "could just use a tad more sugar" and stop there).