I've had puppies on pheasant at less than 7 months. As long has they've had significant bird exposure and are retrieving pigeons/quail well, there's not really an issue.

Personally, I've used Cooke Canyon and Reecer Creek for dog training in the past. Cooke Canyon, IMO, is a much better set up. They have very realistic ground cover, unlike Reecer Creek. Bird prices are about the same for either, although it's a little cheaper if you buy the membership at Cooke Canyon. http://www.cookecanyon.com/
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"If fishing is like religion, then flyfishing is high church." -Tom Brokaw