Your older babies probably help your younger one whenever they get a drink themselves. I put an older baby in with my littles as teachers to make the transition easy. All you need is one bird in the group who knows how to do it. The chicks nudge the pin sideways, not straight in so it doesn't take much force to get water. I figure if a 2 week old quail can do it, a chick should have no trouble. My jumbo brown coturnix switch to the horizontal nipples at two weeks old. All of your birds would rush to a mud puddle if one suddenly appeared! It's hardwired into the chicken brain.
