This is pretty much normal for brand new layers. Did you by any chance restrict them from the nest boxes before? Usually, pullets approaching point of lay are drawn to the nest boxes a couple weeks before they lay the first egg.
They makes a huge mess, "playing house", and a lot of folks just block off the nests because they don't want the mess. The pre-play gets the pullet accustomed to the nest boxes, but still some don't make the connection right away. I've found new pullet eggs in some strange places, sometimes right beside the nest boxes.
Laying their egg from the perch happens when new layers aren't quite sure yet what it feels like when an egg is needing to be laid, and they end up dropping it wherever they happen to be at the time.
The good news is your pullets will figure it out pretty quickly. You really don't need to do much of anything other than if you see them curling up in an inappropriate place, gently move them to a nest box.