I reckon with a chimney starter and a 47 cm BBQ, it takes 15 - 20 minutes/one bottle of Spitfire to be ready to cook. Less perhaps if there's a good breeze blowing.
BTW, this Weber came from the US "base exchange" (or whatever it's called?) in Garmish in 1984. New undercarriage, vent controls and grills in 2008, though, and no signs of corrosion on the kettle.