My pullets tend to lay in the run at first, instead of in the nest boxes. It can take them a few weeks to consistently use a nest box. If the eggs are clean you can pop them into the nest box to supplement the golf balls. Or just add more golf balls. The girls will figure it out eventually.
I tried shredded paper in my nest boxes and hated it because it glued itself to the eggs and was difficult to get off. Plus it blew all over the place when it got kicked out of the nest boxes. I had little shreds of paper everywhere. Now I use pine shavings. Some of them stick to the eggs but unlike the paper I can usually brush the shavings off. And the chickens use the boxes with the pine shavings, so it works for them too.
This time of year eggs can sit in that nest for a couple of weeks and be okay. Think about it. When a hen is starting to go broody, she will lay an egg a day in her nest until she has a bunch of them to sit on. That can take her a couple of weeks. The eggs don't develop until she starts to sit. Which she doesn't do until she has a full clutch of eggs laid. The eggs don't rot during that time because if they did, they wouldn't produce viable chicks. I've had broody hens hatch chicks in June in Tucson. So with highs in the 80's and lows above refrigerator temps I wouldn't worry about leaving some eggs in the nest boxes as learning cues. You might want to mark the eggs you leave with "laid on" dates, so you know how long they've been in there.
j/k have fun with them, chickens are great for your health, taking care of them I mean 
