I have had a baaaaaaad experience with 'chips away', there may be other mobile places who can touch in some small areas and do a real good job. ...ask for examples of previous work.
I have been told by a few bodyshops that the paint the 'mobile' places use tend to be of very low quality anyway, and doesn't tend to give a good finish.
Personally i would wait also untill they are bad enough for a panel to be done, although i believe that metallics are difficult to match (reflective nature of the metal flakes) so a full panel may be better .......