Your first screenplay is always crap.
That's what rewrites are for.
Dont' be worried about your first screenplay. Just do it. Finish everything as best as you can within a week. Don't be paralysed by fear of failure. As long as you do it, you can work on it.
Someone once said, it is better to edit bad copy than to try to edit nothing.
By finishing something as least you have accomplished something and gained the experience of doing it. No matter how bad you (think) it is, it is a learning experience in itself.