tails uses Gamemaker as well(or has used) and has produced very good things, I wouldn't try to argue "its difficult"
Hell, I used it back in the day. When I was 7. Don't give me this "difficult" stuff.
Beyond that, you shouldn't release a demo before you have more in it.
Like you said, it is not a one-second-thing. Therefore you shouldn't release it one second after you start the project.