Would it be wrong if I threaten to quite earlier than I planned to?
Why would you threaten to quit?
I don't know I have been thinking about it for a while
It is wrong to make a promise and then not fulfil it. If you need help you should ask to get it done right the first time.
It's okay, since I made my co-worker complete the tasks I can be a dick and threaten to quit.
It's important to fulfill your obligations. This will help people to know that you are reliable.