I started walking Freddie pretty much right away. We've sloooowly increased the distance of his walks because he gets distracted and then I get frustrated, so it's mostly for my own sake lol.
Freddie sometimes refuses to walk, so I basically walk him when I noticed he has a huge excess of energy and needs some structure and exercise. Since it's been so cold lately, we've just been playing fetch in the house and he runs and runs.
I tend to take him on about a 20-30 min walk. We basically do a 2 block square (small blocks).