Hi TheJame,
It's good that you asked this question. The GMAT score that you earn is valid for 5 years, so if you plan on applying to Business School in 5+ years, there's a possibility that your GMAT score would not be valid by the time you applied (and you'd end up having to retake the GMAT).
In answer to your other question - "NO", Business Schools would not look down on your application if you took the GMAT years before you applied to Business School. Taking that type of proactive approach is actually a really smart thing to do and gives you a far greater chance to hit your score goals than someone who tries to cram in everything (the GMAT and the applications) in the last couple of months before the application deadlines.
GMAT assassins aren't born, they're made,
Rich