[[ That’s a good question! He may have been, and he may have not been. Something like this is actually not answered in the novels, so it’s up for reader interpretation.
Personally, I think Itachi might not have been. What we do know from the novels is that Itachi dedicated his free time to training. Sasuke was also incredibly important but by training, he was getting stronger in his goal of protecting Sasuke, therefore, it was for Sasuke. So training, especially when Shisui came into the picture, generally came above Sasuke, purely because in the end it was for his little brother. He may have easily missed some developmental milestones.
The novel mentions things like Sasuke slowly learning to talk, not that it’s the first time Itachi’s ever heard him speak, etc. Mikoto most likely took primary care of Sasuke (as is fit), with Itachi as secondary care (when Mikoto is out), and Fugaku as tertiary (his job has him out more, he’s also the Captain of the Force and Clan Leader so he has even less time on his hands.) Mikoto has the most free time (time spent in their house) as she is a house-wife.
I don’t think Itachi would’ve been too bothered by missing him walking for the very first time, he’d be glad his brother achieved something. Sasuke could drool all over his shirt and he’d be proud. ]]










