Your PeeGee Hydrangea is a pretty hardy bush that could remain a bush or become a tree if trained properly. It is common for PeeGee hydrangeas to attain height/width of 8-10' so choose a location with that size in mind. Select a spot where the plant receives a little protection from the sun during the summer time (usually after 3pm).
As far as when to plant, it is a bit early to plant it outside so wait until the average date of last frost for your location. For NJ, that can be from mid April to mid May. Consult with a local nearby nursery for the date applicable to your area. Then plant the shrub around that date or, better yet, since the date is an average, wait two weeks after the average date of last frost.
In the meantime, let it get some bright light or direct sun for a few hours in the morning. Water it when the soil feels dry or almost dry when you insert a finger into the soil.
Hydrangeas in the northern half of the country can be fed once a year, in June-ish, using a cup of compost or cottonseed meal; you can also use a general purpose slow-release chemical fertilizer like Osmocote. Then maintain about 3-4" of mulch up to drip line (or a little further if the area is windy).
But on its first year in the ground, you may not need to fertilize it all if the plant's potting soil already came with those round fertilizer granules, added by the nursery. If that is the case, fertilize in June 2011. And feel free to add coffee grounds throughout the growing season. Because early frosts in Fall can zap tender young leaves, do not apply coffee grounds or fertilizers after July-ish.
Once planted in the ground, use the finger method to determine when to water. During the first two weeks, insert a finger to a depth of 4" and determine if the soil feels wet, moist or dry. Then water only when the soil feels almost dry or dry. Each time that you water, make a note on a wall calendar. After two weeks, set the prinkler to water 1 gallon of water on the same frequency (every 3, 4, 5/etc days). As the temperatores change 10-15 degrees and stay there then use the finger method again. You will need to water more often in the summer and reduce watering in the Fall. During winter, on years when winter is dry, water once every two weeks provided the ground has not frozen.
Most hydrangeas sold commercially should be old enough to start blooming right a way. PeeGees should start blooming in June where you live; earlier in the Southern States.
In their first summer, it shold be normal to observe wilting of the leaves. This is usually common on the first year but, as the plant becomes established in your bgarden, the problem should be reduced on later years. Wilting occurs when the leaves loose mositure faster than they can absorb it through the roots. And most hydrangeas will be fine once the sun goes down. If you observe a severe wilting episode, add 1/2 gallong of water right a way. But if the wilting episode does not seem severe, use the finger method to see if the soil is moist. If the soil is dry ten add 1/2 gallon of water. If the soil is moist or wet, do nothing and retest with the finger method in the morning.
Here is alink to a website with much more information on hydrangeas. Go over it when you have some time: www.hydrangeashydrangeas.com
And enjoy your new PeeGee!