Answered May 2nd, 2019

Kyrie Irving posts the first 50-point game of his career with 55 points in a Cavs win over Portland. It was the most anyone had scored against the Blazers since Kobe in 2007.

When was the first time Kyrie Irving had 50 points in a game?
Interpreted as:
When was the first time Kyrie Irving had 50 or more points in a regular season game?