1. Wait until fermentation is complete. Don't measure your fermentation by days, "visible activity" or anything else. Once your specific gravity has remained steady for 2-3 days, then you want to wait a few days to let the yeast clean up any off-flavors it may have created.
2. Cold crash your beer first, then add your dry hops.
You won't create any off-flavors or aromas.
Brody's Brew House
Primary: Scottish Strong Ale
Seconary: Don't use one, generally
Kegged: Sweet Potato Saison
In the fridge: Czechvar, New Belgium sampler
Planned: Either a Porter or an AIPA. Possibly a RIS.
"For a quart of ale is a dish for a king." - Shakespeare