Was the Tee in a freshwater tank? Blackworms live in freshwater, I am assuming you know that.
If you have freshwater in there and are cycling it with some dead shrimp, worms or something else, I would say a month should do it. But I would also add a small portion of worms. The worms will assure the correct bacteria grows. After you get the thing cycled to where you can add an ounce of worms, then gradually add more of them until you can safely keep however many of them you want. The first batch may become a slimy mess, that is fine. Eventually you will get there. My culture if going for many years and I think I can add as many worms as I can get. But never clean it or let it dry. Also keep water moving or it will also become a smelly mess even if it is cycled.
If you have freshwater in there and are cycling it with some dead shrimp, worms or something else, I would say a month should do it. But I would also add a small portion of worms. The worms will assure the correct bacteria grows. After you get the thing cycled to where you can add an ounce of worms, then gradually add more of them until you can safely keep however many of them you want. The first batch may become a slimy mess, that is fine. Eventually you will get there. My culture if going for many years and I think I can add as many worms as I can get. But never clean it or let it dry. Also keep water moving or it will also become a smelly mess even if it is cycled.