From chicken to egg there is always an evolutionary step, even when it is a very very small step.
From egg to chicken there is no evolutionary step.
So the egg comes first, and then the chicken.
I apologize for the OT, but the nerd and biologist inside me just can't help it... I promise this will be my last post on chicken and egg.
An egg is a part of the chicken. How can one part of the chicken be a step ahead in evolution over other parts of a single body?
Would a human egg be an evolutionary step ahead of human? Yes, human has eggs too. The only difference between a human and a chicken is the chicken lays the egg and lets the egg mature outside her body. A human female allows her fertilized egg mature inside her body.
Almost all living beings have eggs, no matter how advanced or primitive. And egg is an integral part of the animal that has the egg. So the egg is the same as its own master animal in terms of evolution.
If we truly want to know if eggs appeared before animal, we need to trace back to the appearance of the first animal that used egg for reproduction. Although I have no idea how eggs appeared, one thing I am sure is that life on earth started as single cell organisms, which are essentially eggs (essentially a gigantic single cell). In that sense, egg came first. However, that doesn't mean egg is evolutionarily ahead. It actually means that the egg is probably the most primitive part of all living beings.
End of OT. The nerd inside me is happy...