did your vet not tell you? If not call them and ask.
My vet said 2 weeks, a friends said 10 days.
However I was told he could go places where no unvaccinated dogs/ foxes would have been (he ran around the barn up the yard for example, and could meet vaccinated dogs). Although there was a small risk my vet was stressing the need for him to be socialised as he wasn't a very forward puppy.
You will always get slight difference of opinion, but it's usally always advised 7 days after the 2nd, this is also the rule I go by, although I do carry the heffers around to let them see the world and drive them everywhere in the car
When our pup had her second jab on tuesday the vet said 7 days before going out on public walks. This precaution is incase they come in contact with unvaccinated dogs, luckily we are able to excercise our pup in private fields with our other 2 vaccinated dogs.