I just got a new 3gen ipad should I charge first before setting it up?

You can use it while you charge it to 100%

FYI

The quickest way (and really the only way) to charge your iPad is with the included 10W or 12W (5W on Mini) USB Power Adapter. iPad will also charge, although more slowly, when attached to a computer with a high-power USB port (many recent Mac computers) or with an iPhone Power Adapter (5W). When attached to a computer via a standard USB port (2.5W, most PCs or older Mac computers) iPad will charge very slowly (but iPad indicates not charging). Make sure your computer is on while charging iPad via USB. If iPad is connected to a computer that’s turned off or is in sleep or standby mode, the iPad battery will continue to drain.

Apple recommends that once a month you let the iPad fully discharge & then recharge to 100%.

How to Calibrate Your Mac, iPhone, or iPad Battery

http://www.macblend.com/how-to-calibrate-your-mac-iphone-or-ipad-battery/

At this link http://www.tomshardware.com/reviews/galaxy-tab-android-tablet,3014-11.html , tests show that the iPad 2 battery (25 watt-hours) will charge to 90% in 3 hours 1 minute. It will charge to 100% in 4 hours 2 minutes. The new iPad has a larger capacity battery (42 watt-hours), so using the 10W charger will obviously take longer. If you are using your iPad while charging, it will take even longer. It's best to turn your new iPad OFF and charge over night. Also look at The iPad's charging challenge explained http://www.macworld.com/article/1150356/ipadcharging.html

Also, if you have a 3rd generation iPad, look at

Apple: iPad Battery Nothing to Get Charged Up About

http://allthingsd.com/20120327/apple-ipad-battery-nothing-to-get-charged-up-abou t/

Apple Explains New iPad's Continued Charging Beyond 100% Battery Level

http://www.macrumors.com/2012/03/27/apple-explains-new-ipads-continued-charging- beyond-100-battery-level/

New iPad Takes Much Longer to Charge Than iPad 2

http://www.iphonehacks.com/2012/03/new-ipad-takes-much-longer-to-charge-than-ipa d-2.html

Apple Batteries - iPad http://www.apple.com/batteries/ipad.html

Extend iPad Battery Life (Look at pjl123 comment)

https://discussions.apple.com/thread/3921324?tstart=30

New iPad Slow to Recharge, Barely Charges During Use

http://www.pcworld.com/article/252326/new_ipad_slow_to_recharge_barely_charges_d uring_use.html

Best Practices for iPad Battery Charging

http://www.ilounge.com/index.php/articles/comments/best-practices-for-ipad-batte ry-charging/

Tips About Charging for New iPad 3

http://goodscool-electronics.blogspot.com/2012/04/tips-about-charging-for-new-ip ad-3.html

How to Save and Prolong the battery life of your new ipad

https://discussions.apple.com/thread/4480944?tstart=0

Prolong battery lifespan for iPad / iPad 2 / iPad 3: charging tips

http://thehowto.wikidot.com/prolong-battery-lifespan-for-ipad

iPhone, iPod, Using the iPad Charger

http://support.apple.com/kb/HT4327

Install and use Battery Doctor HD

http://itunes.apple.com/tw/app/battery-doctor-hd/id459702901?mt=8

To Extend a Device’s Battery Life, Get to Know It Better

http://tinyurl.com/b67c7xz

iPad Battery Replacement

http://www.apple.com/batteries/replacements.html

In rare instances when using the Camera Connection Kit, you may notice that iPad does not charge after using the Camera Connection Kit. Disconnecting and reconnecting the iPad from the charger will resolve this issue.

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Since you are a new iPad user .....

Complete guide to using iOS 6

http://howto.cnet.com/ios-6-complete-guide/

Guide to Built-In Apps on iOS

https://sites.google.com/site/appleclubfhs/support/advice-and-articles/guide-to- built-in-apps-ios

You can download a complete iOS 5 iPad User Guide and iOS 6 iPad User Guide here: http://support.apple.com/manuals/ipad/

Also, Good Instructions http://www.tcgeeks.com/how-to-use-ipad-2/

Apple - iPad - Guided Tours

http://www.apple.com/ipad/videos/

Apple iPad Guided Tours - Watch the videos see all the amazing iPad apps in action. Learn how to use FaceTime, Mail, Safari, Videos, Maps, iBooks, App Store, and more.

http://www.youtube.com/watch?v=YT2bD0-OqBM

http://www.youtube.com/watch?v=ROY4tLyNlsg&feature=relmfu

http://www.youtube.com/watch?v=QSPXXhmwYf4&feature=relmfu

How to - Articles & User Guides & Tutorials

http://www.iphone-mac.com/index.php/Index/howto/id/4/type/select

iPad How-Tos http://ipod.about.com/lr/ipad_how-tos/903396/1/

You can download an iPad User Guide to the iPad from the iTunes store.

 Cheers, Tom 😉

If the iPad has sufficient charge you can go ahead and use. You can charge it while using it or wait until later.