I would suggest making the hole smoother. And clean all the paint and rust away. Round the corners. Then hammer the edges flat and straight. Then take your patch piece and, if you can hold it from behind, trace the hole on to the patch piece. If you can't reach behind, use a magnet. Then go trim your patch piece. Sneak up to that line and leave a lot of the line there. Test fit, trim a little, test fit, trim a little, repeat. What, you have a car show to go to next week? No, you have plenty of time. If rain is coming, walk away until the rain goes away. In other words, don't rush it. Like any job that isn't rushed, you'll have a better result. Same with when you start welding. Take your time, don't rush it. Check it often to see which way your metal is moving so you can react accordingly.
