christyf5 has a sticky on a whole lot of reading on LR
http://www.canreef.com/vbulletin/showthread.php?t=22062
I would suggest to use as much LR as possible, I went with just under 1LB / Gallon. Your tank will be up and running a lot quicker with cured LR rather than without.
If you have time, read through as many posts on here as you can to learn from fellow Canreefer's experiences. Hopefully you can learn from someone else's mistake rather than your own.
If you don't have time, MAKE SOME! Believe me, it'll be worth it!
Good luck!