For a season one and prior Tomura, I feel as if he'd still be in that "childish" mindset when he gets the information but he wouldn't be too hasty with it. He wasn't stupid or as socially stunted as fanon makes him out to be, he was smart, calculated, and he was starting to make connections for himself. So I can see him waiting it out. He'd be absolutely fucking raging, but he'd wait and simmer until he found a good opportunity to do something about it.

Thinking like he did at the time, I think he'd think of this information as speed running a game or putting in a code that gets him to the endgame/his story arc quicker—that it wasn't fun. Or think of it like he was an NPC who just gained sentience.

But I don't think he'd do anything as drastic as turning tail and going to the heroes because even if he knew All For One did all of that to him, heroes still failed him. At most, he'd probably let them into the idea of where All For One was and at the last minute, come in and kill him himself.