I've touched up more chips than I care to admit, and I normaly just wait an hour or so. Just don'y go crazy with the sand paper. I've also come to accept that no matter how good you get at repairing paint chips, you will probably be able to see some imperfection when done. Most, if not all othes will never see a thing and think your nuts!:bounce
Another little tip is to fill the chip in stages a little at a time until the new paint is slightly higher than the original finish. Use a piece of 1500-2000 grit paper on the end of a pencil eraser with lots of water. Check your work OFTEN!!!!!!! You can always take off more, but you can't put it back.:shocked