score:7
I'd say Half-Uncial (3rd Century AD) and Carolingian (9th Century AD) scripts; as it says in the Wikipedia text for the latter,
Clear capital letters and spaces between words β norms we take for granted β became standard in Carolingian minuscule [...]
So it was the first time both capitals and minuscules were used in a standard way (instead of ocassionally as with previous minuscule scripts). I don't think it would be possible to pinpoint exactly which was the first text ever to use them together, though.