From everything I've learned here from the *feed gurus* higher protein is better, and the "layer" option isn't actually the best option. Seems like many people go with an "all flock" type that has lower calcium and let then hens get what they need from supplemental oyster shell free choice.
I don't think Scratch & Peck has an "all flock" that is low in calcium, so if you want to stay with that brand, it might be good to keep them on grower crumbles (it's at 17% protein) and either ferment or wet into a mash (to get all the fine powders used up), and give the oyster shells on the side.
Again, this is all from what I've learned here. I'm still raising babies and I have them on the Scratch & Peck starter, but I think I'm going to switch to Nutrena NatureWise All Flock pellets (20% protein) later and then start giving oyster shell when I see them getting close to POL.