BY THE TIME - BY
We use by / by the time to say that a situation will continue up to a certain moment. After by we use a point in time.
*** By Tuesday, we will have finished our homework.
*** By the 16th century, Turks had settled in Anatolia.
After by the time, we use a sentence.
*** By the time we got there, he had already left.
*** By the time the teacher comes, we will have taken our seats.