WIN XP SP3 USB 2.0
(I am allways turn on device before connection)
NUVI 1xxx - less 10 sec
NUVI 37xx - less 10 sec
NUVI 2x5 - depend of software and hardware
NUVI 7xx - more 30 sec (due initial loading map every times - long green stripe)

When I changed device for other series there was 1-2 minute process sometime.