
Hi,
You should start taking your pup out for 'carries' rather than walks as soon as you get him, until he's completed his course of jabs. Then he won't be so scared at some of the things he sees when you can start taking him on the pavement (at 12 weeks, or whenever your vet advises). These 'walks' at that age won't be for exercise, they'll be for socialisation and training, so 5 - 10 minutes will be ample.
Hope this helps.
:)