Body help/advice needed

Got started on the first fender. Cut out the worst and started making the patch. Here are some pics.
DSCN1773.JPG DSCN1774.JPG DSCN1776.JPG DSCN1779.JPG
Hope to fit the panel today and try welding a little. I got a piece of brass to put behind the welds to help remove heat. Also will only do small spots at a time allowing for cooling before hitting it again. Should I tap fender edges in at all before welding or just clean up as it is and then match and weld the panel. First time doing something like this.
Thanks Rod