It is not really fear but apprehension. Not knowing what to expect as this is new. Be patient, be involved and everything will come to you.
Things will change. However these changes are for the better. There are steps in life that you can't make on your own and this is one of them. Your child will move you along at your child's pace and you just need to be there for them.
In the end when they call you "daddy" and give you a big kiss it's a prize 2x the size of any lottery. There are people out there that spend a fortune just to be in your shoes.
Just remember they will always need you. No matter what problems come from other people around you your child is just that.