If the recipe you're brewing calls for a dry hop in 7 days... by all means huck 'em in there.
Butr I think it might be a tad early.
But... I'll offer this... you can do it or not... up to you... you really don't need that secondary. Even to dry hop. You can leave your brew in the primary, and dry hop right in there.
ALL my beers go to 14 days primary fermentation. If I need to dry hop. I just huck them in the primary and let them set for another 2 to 4 days. Then rack right to the keg after that. I don't brew crazy high gravity beers with weird concoctions. I brew what I like to drink. Amber ales, Pale Ales, and the occasional Oatmeal Stout, and they all go to 14 days in the primary. The only one I do, that I've racked to a keg at the 10 day mark was an American Hefe for my wife. All in the primary fermenter.
Nowthen... you can definately use a secondary if you wish. Just offering up, that you really don't even need to use that step in the brewing process.
Happy brewing!
Gary