Final answer:
The correct punctuation is "Whether I like it or not, by tomorrow, I must choose a college to attend." The clause "by tomorrow" is non-essential.
Step-by-step explanation:
The correct punctuated revision of the sentence is: Whether I like it or not, by tomorrow, I must choose a college to attend. The clause "by tomorrow" is non-essential.
Learn more about Correct punctuation in a sentence