How To Preserve The Timeline & Other Plans Midoriya Ignored

Midoriya Izuku wasn't in the best mental space when the decision to send him back in time was made, but he promised he'd do his best. There were plenty of plans made beforehand, and plenty of information he had to memorise. He had to lay low, try and keep the timeline as close to the original as possible while gradually making it a better future.. not likely.