If you have some online business plans but are in no hurry to get it started, it would make good sense in registering the domain name right now itself. Good names are always taken up and by the time you are ready to set your site online, the domain name of your choice may not be available.
What you should do is register it right away. Till the time it is not pointing to your site, it will show your registrar’s default holding page. This is called Domain parking.