The 'Charcoal Grill Owner's Guide' actually advises the quantity of fuel to use for all Webers using either charcoal briquettes, beechwood lump charcoal, mixed wood lump charcoal or Weber heat bead briquettes.
They supply a charcoal cup with which to measure the correct amount of fuel; for example, for the 47 cm kettle use 30 briquettes or 1 cup of lumpwood charcoal.
I reckon on about 25 minutes from lighting to starting cooking, using the briquettes from the local supermarket.