Statute of Limitation on Personal Loan

QUESTION 1: Do you accept clients who are private individuals trying to collect a debt from another private individual? And if so, may I inquire as to your rates and whether you employ paralegals on small, simple cases so as to defray costs as much as possible?

BACKGROUND:

In rather exigent circumstances, I loaned my brother $12,537.90 at a 12% annualized rate of interest. He signed a Promissory Note to that effect on July 20, 2016.

The final payment should have been made on March 1, 2018, but during the entire scheduled period of planned amortized payments, he made NONE.

He did thereafter subsequently make three small payments, the last of which was made on April 30, 2018.

QUESTION 2:

Will the original 6-year statute of limitations on a personal loan run out on:
1) July 20, 2022 (6 years after he signed the Promissory Note)
2) March 1, 2024 (calculated from the final scheduled unpaid payment due date of March 1, 2018), or
3) April 30, 2024 (6 years after he made his last payment on April 30, 2018)?

(I’m pretty sure it’s #3, but please confirm.)