How much time did it take Yuu Otosaka to fulfill his promise to Tomori?


I just finished watching Charlotte and I'm curious as to whether it is
mentioned anywhere how much time it took him to fulfill his promise?




He lost his powers after using them multiple times per rotation. So, keeping
in mind he made travel back-and-forth multiple times, and to keep increasing
his profits, it might have taken more than 2 years without the powers if we
take into account the time he spent traveling. But based on his promise, it
only took him around 2 years to increase profits and start the school.

