I give my 4 girls 2 hard-boiled eggs for 'breakfast' about 2-3 times a week. You should crush them (shell and all!) real fine...then stand back because they will be CRAZY for them!
Nothing unusual at all...not to worry. When your girls start laying, at first it's kinda hit-n-miss while their little bodies are figuring out the whole egg-laying thing. When mine first started (I have 4 Black Australorps) my first one to lay didn't lay again until 2 days later, then the next...