Depends.
I have a large t-shirt wallhanging I haven't gotten around to quilting and binding. That's going on about 8 or 9 months old.
Right now I'm working on a series of stained glass style wallhangings based off some windows in one of my favorite video games. I've been working on it since January, but I had the idea since '07 or '08. I even tried to attempt making it back then, but gave up when I couldn't find good images to work off of. So if that counts then my oldest would be 3-4 years old.