Typically, we like to take the primary attribute to a higher cap asap to reap the greatest reward from the natural gains you will see through leveling. In many cases, if you hit a relatively high cap soon you will never need to add points to that attribute later. The natural gains, however, diminish at key level plateau's, so the sooner the better. Much of that info can be found in wiki tab at the top of the page or, here -
http://www.glbwiki.com/index.php?title=Leveling