one thing to remember is that much like doing a startup in general, there are no hard and fast rules about getting YC funding.
YC had every reason not to invest in us - we weren't technical, we already had angel money which complicated issuing new shares and we were based in the UK. they still funded us.
YC funding is less about worrying about all the reasons you won't get funded and concentrate on making as many reasons why they will fund you.
I know of cases where cofounders met at startup school, but we haven't funded any. The most ad hoc group of founders we funded were a pair who knew one another online but hadn't met. That didn't work out very well.
I would imagine such a situation to be dicey. Startups are forged around shared passion, trust, and ability to work well together, not too different from marriage. Using the marriage metaphor, I think going into business together on a first impression puts you and your cofounders in a tight spot.
It's not automatically dicey. My cofounders and I found each other specifically for the purpose of starting this business. We're four months into our venture now. We get along extremely well, our skills complement each other nicely, and we have a lot of faith in each other and in our business. I can't imagine having a working dynamic as strong as this one even with my close long-term friends.
I see what you're saying, but, to a certain extent, you won't be able to test what your team is truly made of until you guys hit that first bump -- this is when things become clearer, and I would imagine you wouldn't want to wake up one morning wondering how you got in that bed in the first place.
Nonetheless, I'm happy to hear that you were able to find good cofounders!
I met my current co-founder at the first startup school. We've been working together for over a year now. Our first (self-funded) startup hasn't really taken off, but we managed to meet an angel investor in in the SF Bay Area with similar ideas to our own and are now working on a new site - so don't give up hope on getting funding.
Though rare, it's also not unheard of for yc to fund single-person startups. I applied as a single founder, with the stipulation that I would find someone before the summer. It all worked out, but I'm also the kind of guy who gets along with most anybody.
This was replicated in at least one other yc startup I know.
The marriage metaphor, as JMiao put it, works well. When you're setting off to start a family with someone, you don't want any adverse surprises. The same goes with starting a company. And similarly, making foundation changes will be expensive as hell, in time and money.
YC had every reason not to invest in us - we weren't technical, we already had angel money which complicated issuing new shares and we were based in the UK. they still funded us.
YC funding is less about worrying about all the reasons you won't get funded and concentrate on making as many reasons why they will fund you.