you don't want to dry hop during active primary/vigorous fermentation as the CO2 will actually carry off a lot of the hop aromas.
if you don't rack to secondary and just do long primaries, wait til you've hit your FG before dry hopping.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10