eggs keep breaking

So my hen just started laying and I know it can take a while for their shells to thicken. My hens have plenty of calcium, so I don't think that's the issue. I think she's laying to many too soon. She layed one good egg yesterday (it cracked because she layed it on the roost and when it fell it cracked a bit) then she layed another which was whole, but very very soft and see through. This morning she layed another (on top of the nesting box instead of inside of it) and when I went in to check the coop this morning it was a thinnish shell (not as thin as the second, but thinner the the first egg from yesterday) and it was completely cracked open and all over the box, but not eaten, so she's not an egg eater. My question is how long will it take for her to self regulate so her eggs are good and strong? I also heard that you aren't supposed to eat their first few eggs anyway. Is this true?