Board Thread:Episode Discussions/@comment-25319479-20170913103410/@comment-2112031-20170913173842

It should be noted that, technically, Sasuke awakened his Sharingan during the Uchiha Massacre, but he didn't notice it and didn't reawaken it until the battle with Haku. Also, Boruto and Sarada are about 12 years old at this point.

As others have mentioned, the Multi-Shadow Clone Jutsu was forbidden because of the risk it poses to the user. Creating multiple shadows clones can leave the user either exhausted and open to attack or, in the worst case scenario, the user can overexert themselves and die.

Naruto mostly avoids this due to his massive chakra supply due to his Uzumaki heritage as well as having a Demon Fox sealed inside of him that can provide him with even more chakra in the event that he starts running out.