We launched 4 years ago with 3 folks and should be 20 by this summer assuming we find the right folks (we're 15 now). Just hired our first biz dev guy a couple of months ago. I'd sold the first couple of million in subscriptions. While I'm not sure if we should have hired a BD guy sooner, my co-founder and I did feel like we needed to understand the sales process first.
The good news is that I'm pretty far from a natural salesperson so if we get this product into the hands of someone who really knows how to sell, we'll be on an even better path. That said, I brought a really solid understanding of the product to sales calls which def helped us.
It's been a great and rocky road. We're about to reach escape velocity I think, and I'm really looking forward to that.
As an aside, I try to convene a group of bootstrapped SaaS entrepreneurs for lunch/dinner periodically to exchange ideas/tips/help one another so if you fit the bill and are based in or near NYC or going to be in NYC, please reach out. (details in profile)