They should be okay, but it's likely that the fertility rate will go down as time passes. However, remember than ducks take a week or two to collect enough eggs to set. They'll leave their eggs for weeks before sitting on them. Duck eggs tend to last much longer than chicken eggs do when left to sit out. I think it has to do with the fact that duck eggs are less porous that chicken eggs.
When you get those duck eggs home, just make sure they are room temperature before you set them in the brooder (or beneath a broody hen/duck). If they are still cool (I'm assuming they were shipped with a cooling pack), let them sit for about 24 hours so they can get to a regulated temperature. At that point, they'll be ready for the brooder.
Good luck with your duck eggs!
