actually, i've heard many instances where, as a newborn, youre the most attached to God you'll ever be.. this might just be folkloric, but like... it's said that newborns are the most attached to god than anyone else. therefore, i'm not sure it's such a waste of time.
also, it's all about developing the habit. sure, it might be showing off, but science, which you have shown a keen liking to, proves that the earlier and more often you make a baby go into a certain routine at different places, the higher the chance that the child will do it on his own as he grows older.
i know this specific case in my city. I know this couple who's son is 2. They would "make" him matha tekh even when he was a newborn, at the earliest of ages. ever since he's been about 1 or 1and a half, though, he's come up and done it himself. sure, he may not know what he's doing, but don't you agree that it's hella lot better than the kid walking in and doin nothing?
and finally, why do YOU matha tekh? do you know why you matha tekh? is it REALLY for respect? or is it to receieve Guruji's proverbial hand on your head, as in blessing? what is actually the true purpose of matha tekh-ing. (i should make that an official verb:
I matha tekh
you matha tekh
he/she matha tekhs
we matha tekh
you matha tekh
they matha tekh)
maybe we're showing off just as much as those parents.... somethin to think about?