I think most of the time you're ok getting it remapped from the beginning, the only problem would be if the car developed a fault you've no idea whether the map may be causing it or whether its a real fault with the car.
I ram mine for 10000miles then got it remapped, that way I knew it didnt have any obvious problems like misfires, so when I did get it mapped, and it started to misfire I could blame it squarely on the map (which was resolved by revo pretty quickly)