My baby boy is beginning to show signs of a potential running partner. He is now 4.5 months, and I heard I should wait until close to a year before trying it out. But now when we go on walks I can say "Clarky let's race!" and we take off together for a couple of minutes. And when I cheer him on "go Clarky go" he picks up the pace.
At least for now he has me walk/jog a little every day, so I get a couple of unofficial miles in on my off days.