My first sewing project completed

Well I've completed my first sewing project! I know its an easy project but nevertheless I'm pleased with it. I followed the instructions but one there is one thing I'm not sure about and wondered if there is anyone out there who would be able to shed some light on it for me....I read that I needed to go around the edges to do the zigzag stitch. The instructions said that I needed to do the zig zag and then cut the corners off to have a nice point when the cushion is turned the right way around. After doing the zig zag around the edge the stitch went right up to the corner so I had no corner to cut off. Should I have done the zigzag right next to the straight stitch? I'm a little confused by it. If someone could provide some advice I'd be grateful. All in all I'm please with the first project and looking forward to the next one!