What situations can 初めてのX and 最初のX be used in?

Question

大谷選手がアメリカの大リーグの初めての試合でヒットを打つ
Ootani makes a hit in his first (ever) match in the American major league.

I started wondering about when you can use 初めてのX. I understand はじめて means 'for the first time', so I'm assuming this is his first ever game for America. If it was his first game in his second season for America, for example, would 初めての試合 still be appropriate? If not, what would you say?

My guess is to use 最初の試合, but I really don't know. I saw this question on the difference between 初めのX and 初めてのX, but I wonder where 最初 fits into this?

This question is also highly related but I'm not sure it quite answers my question.

Answer 1

short answer, you are correct about hajimete vs saishou. 初めてのX is the very first of X, singling X out as a special event, not taking any other future events into account. 最初のX is the first X of potentially more than one, and the implication is that more will likely follow. so, 初めての試合 can only be that person's first ever match (or first ever match with a given team, as that would be an acceptable event to label as a "first ever") but 最初の試合 would imply the first match with at least one more match to come. And you would not use 初めての試合 for his first match of the second season of the same league or for the same team. 最初の試合 is the appropriate choice there.

Special "firsts" always use the 初めて form: first kiss, first love, first time you ever saw/heard/learned about X, etc.