It's not a very good idea. There isn't enough energy in a 9V battery to charge a phone. Using a low drop-out regulator or a buck converter would be much better, as there's still plenty of energy left in the battery when the LM7805 will go into drop out i.e. stop regulating properly.
It could also be much neater. To make a slot for the connector, drill a few holes to make a rough slot which is still too small, then file it to shape. It will be much neater and look far more professional. Don't use a soldering iron to make holes, that's what a drill is designed for.