How long after the second injection can a puppy go out

It depends on the local area and how prevalent disease is, but it's usually 10 days to a fortnight. Of course you can keep on carrying them everywhere to experience the world.

Our vet said 1 week, so today is the day for us to venture out for the first time! Very excited as we've had pup for 4 weeks. We probably won't get far though!

Remember the the " 5 minute per month rule ", so if 3 months old then 15 minute walk per day[ 7.5 minutes out and back]

Enjoy introducing all the new sights and smells, sit on a bench in an area with lots of foot traffic and reassure the pup if anxious and praise if doing well,give a treat with each new experience that it has coped well with so it connects the two.