I suppose it depends on the definition of “attack” – and “attack” does not mean “strike”.
The moment an “opponent” (which could just mean some random hoodlum who chooses to harass you) makes an offensive act with the intent to continue/escalate such acts, that’s the “first attack”.
The intent to continue is the key: some moron walking by and saying “nice shirt, sissyboy” and continuing to walk by is an idiot, but not an attacker. The same moron grabbing your shoulder and saying “nice shirt, sissyboy” obviously has the intent to continue. Even in the latter case, de-escalation should still be attempted, but in Funakoshi’s perspective, you have been “attacked first”, and you should prepare a response. In the former, you should still pay attention and be prepared for some form of continuation, but it would not be considered a first attack in-and-of itself
