K.V.
I think my boys were closer to 2 yrs when they started using pillows. I agree, 9 months does seem a bit young....how well does she roll over & hold her head up? That's kinda the key to your answer. My youngest was congested & had frequent colds (thanks to his older brohter being in preschool!) the 1st year so I bought a wedge at Baby's R Us that I put on top of his mattress & under the fitted sheet. It helped tremendously so maybe you could try that. You might want to ask you ped. about the pillow usage before you continue. Best of luck!