Is there a time restriction where the repo man can't knock on my door?

Yes, per the FDCPA (Fair Debt Collections Practices Act) contact can only be made from 8:00 AM to 9:00 PM seven days a week, at your home. There is no restriction on contact at your place of employment. Here's the thing, in most cases, if it is 10 or 11 o'clock PM and the repo agent sees your lights and TV on, he may do you the courtesy of letting you remove your personal items in exhange for the keys. Two reasons for this: first, if your personals stay in the car you will pay a storage fee to get them back; and second, with the key he can more easily unlock the shifter and steering column and can more safely tow your vehicle. The second part is important to you because if you redeem it, you will not be redeeming a stripped transmission/differential or wrinkled fender.