Agreed! Mine are different ages so some laying/some not and 3 roosters. When you find yourself in that situation (and with chicken math you will lol) it's easiest to feed everyone grower or all flock and just provide a dish of oyster shell for the hens that need it. A bag of oyster shell isn't...
Congrats on your first egg!
I have found a small dish of free choice oyster shell separate from their food to be the easiest. Your hens will know when it's time to nibble on it and if not laying yet they may peck out of curiosity then leave it alone. I'm not positive if shells provide the same...