Perfect place for family trip!
If i remember right, I made reservations to PR exactly 12 months prior to trip start date, so i would say Aug 1st, 2012 for Aug 31st, 2013 trip date. Well, i also used 4 phones to call Xanterra number, when the window opened up
For lodging at SR and NR, they open up 12 months in advance, so i reserved them as and when it opened up.
Transcanyon Shuttle between SR and NR was like 4 months back, Dining reservation opens up only 7 days in advance at NR and SR BA lodge dinning doesn't accept reservation but you have loads of options out there.
BTW, Canyon lodge at NR does provide complimentary shuttle to North Kaibab trailhead at 5.30am and another one at 6am. You can only reserve spots a day prior to the start date. That being said, whoever shows up first, gets picked up and they happily do another trip if more than 12 people are seen.