New curtains nearly always look a bit stiff on the first day.

New curtains nearly always look a bit stiff on the first day. Nothing wrong with the fabric. They just haven't been trained yet.

Once they're up, draw them right back into the stack and run your hand down each fold, heading to hem, so the pleats sit evenly.

Then tie them loosely in three places with strips of soft fabric or an old pair of tights. Not tight enough to crease.

Leave them three days, a bit longer if they're interlined, and open them as little as you can.

Untie them and they'll fall into the folds you gave them. Skip it and they find their own shape, which is rarely the one you paid for.