It started small, naturally. Tiny, just a few minutes. Then hours, then days, then weeks. It was jarring, certainly, but Hermione wasn't sure she could turn back at this point even if she tried. Why would she do that, though? She was two years older than her friends. It could seem like a small amount, until she considered that those years were made up of hours. She'd manipulated time so frequently she'd lost count. "Prolonged exposure" was a bit of an understatement at that point.