If its damp, or cool outside it'll take longer. I did some this winter in my shop, cools down pretty quick if i don't keep the fire burning. It took overnight to harden. It should be fine. With the bondo, you can usually get it to set pretty quick, 15 to 20 minutes till its workable with a file. Dried hard soon after.
Maybe you'll have an epiphany while your sanding the hood down

.
OR
You'll probably wake up and say, ya, thats it, thats what she'll look like.
Ad