To me, quinoa by itself has a sort of bitter taste. Josie (age 4) and I like it with garlic, butter, and tamari sauce, although you might find that combo a little much for only 8 months! (OK, maybe just the garlic!
Actually, come to think of it, adding spices to it, like maybe some cinnamon, might be nice. Are you pureeing it? It might be the texture.
How about a more mellow-tasting cereal grain like millet? It does take longer to cook but tastes nice and grainy. I pureed some quinoa together with millet and my last bag of frozen EBM for Natalie and I mix it with whatever I'd mix with any cereal (usually veggies here) and it seems to go down just fine.