You'll be using a 1/4 inch seam allowance. I thankfully have a nice presser foot a 1/4 inch notch in it, so I just keep the edge of the fabric lined up with that.
Start at the bottom of the turning opening and sew all around the bib to the needle marking the top of the opening. Make sure to backstitch at the beginning and the end.
Around the neck of the bib, you'll need to go nice and slow and really manhandle the fabric to where it needs to be. I also left the needle in the fabric and raised the presser foot a couple times in tight spots. :D
I like to press the bib after I've sewn around the edges, but you don't have to!