About how large is large for the squash? Can I prepare a day in advance and cook before serving?

Amg- You can cook all the components, blind bake the crust and leave the assembly for day of. P.S. Remember to blind bake, I got ahead of myself and skipped; by error; the blind bake and my crust was mushy although still delicious!

My squash was 3 lb and I roasted all of it then spread the carmelized onion and the roasted squash over the onion, it took about 2/3 of the squash. I just ate the leftover squash as a meal. Next time I use a 2-2.5 lb squash