I think a bigger problem for you is the use of "I", YC is very much focused on the team. If you've got a good team with a track record from working together you've got a chance to get in pre-product.
If you're a sole founder you pretty much have to show that you're capable of building a company on your own which essentially requires product and traction.
Thanks for asking this question. I was wondering this as well. It's good to hear that very early stage ideas are not shunned altogether, even though we are at a disadvantage to other candidates.
I'm currently following David's advice; questioning my idea using YC application as a reference and starting to get a prototype together.
Considering that YC encourages people to apply even if they don't have an idea, and pg has stated in these forums that they accept founders who don't have ideas, you're probably fine.
I am looking for partner to apply for YC. I am a techie with 8 yrs of experience in developing software products. if interested, shoot me an email.
I don't think it's too early to apply for YC. We hadn't built anything when we applied (although we had spent a few weeks brainstorming ideas). We built our prototype between when we were accepted for interviews and when we actually interviewed. Even if you don't apply, filling out the YC application is a great way to think clearly about your idea.
YC accepts good people who's ideas they don't like and then try to convince you to do something else. We fell into this category. I wouldn't spend too much time writing a business plan though. Start building things and experimenting.