8 x 9 feet is 96 x 108 inches
A twin mattress is approximately 38 x 80 inches
Assuming that the 8 foot measurement will go crosswise - that gives you 29inch overhang on each side.
I do not know your preference for how you cover - or don't cover - your pillows.
If you only have the quilt go to the top of the mattress (not over pillows) - then you will have a 28 inch overhang at the foot of the bed.
Is your bed very tall/high? Some beds are so high, one almost needs a ladder to get to the top of the bed.
It might be more manageable if you went with a bed skirt and have the quilt only go a couple of inches over that.
Remember that quilting "shrinks" the quilt - the denser the quilting, the more "shrinkage".