I have done that in the past too Luda, since we always go out at 9:30am for our morning outing it is perfect if I have a child who naps while we walk to the park or the library, then stays awake the rest of the morning.
My worst nightmare is that the child falls asleep at 11:30ish on our way home just before lunchtime and naptime, aaargh! I get the other children to check on and talk to that little one to keep her awake. We have one right now who does that and she's 17 months old. But distracting her with a leaf or rock or squirrel watching works well as we walk home.