Can this be made a day (or 2) ahead?

oh, absolutely! think of it like any pie. in the summer, I have one on my counter at all times, and we eat a little every day until it's gone. then we repeat! this summer i started added peaches to the bluberries. highly recommend.

While I wouldn't make and bake the whole thing ahead, since it would likely get soggy, I see no reason why you couldn't prep the dough in advance and keep it in the fridge for a day or two. That would cut down on prep time the day you plan to serve it. I do this with pie crust all the time.

It should be edible for a few days, but the crust will be deteriorating pretty rapidly; really a lot better fresh.