Here's the problem. Kakashi and Zabuza are the same age, and Zabuza graduated at the age of 9 when the Village of The Blood Mist fiasco was going about. At least that's what the databook says, the manga states that it was 10 years before the fight with Kakashi and Zabuza, but Kakashi was 26-27 around that time.
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If we go by the manga Obito would have been roughly 16-17 years old, if we go by the databook he would have been 9 in a point in time when he didn't even have his Sharingan yet. As we know now Madara couldn't have been involved, so my guess is that it was 16-17 year old Obito. Either way I think it's dumb as hell that in a time span of 3 to 4 years this fodder kid who couldn't even fight without having goggles on was able infiltrate two villages, control the Kyuubi, fight toe to toe with Minato, and defeat a Kage who was a Jinchuuriki.