DO NOT hire a BD person.
First, a startup with <$10m/yr revenue almost surely has nothing to offer another company that is interesting to them for BD. Not enough attention, not enough users, not enough revenue-sharing, etc..
BD only works when BOTH sides move the needle on something important to them, which usually means revenue but it can mean attention or branding or something. If you can't fulfill your end, then it's not BD. It's something else, like trying to be an affiliate.
Also, people who's title in LinkedIn are BD are not the sort of folks used to moving the needle for startups.
I have literally *never* seen a person with the title "BD" at a startup make a difference. Usually they're the subject of ridicule behind closed doors.
Not to say there isn't the person who could. I know a CEO of a startup that currently does $20m/yr and he's the definition of the consummate BD guy. But you cannot bet yourself on finding that unicorn.
Business Development, like Marketing, should be brought on when the product is ready. That usually means that there's a great understanding of your core customer, the use case, and a business model that scales.
I would suggest doing atleast 3 business development deals first to test the model, perfect the process (i.e. comp structure, requirements, marketing assets, agreements, etc) - then if they work, you can bring someone on to go after other identified (similar) opportunities.
Just because you have a lot of inbound opportunities to partner doesn't mean you should - be sure to focus on the product, API's (they are the future of BD) and business model to ensure they can support a successful partnership.
No sense in doing a campaign where you loose 30% of your margins if you only make 15% = You're loosing money on those deals.
It happens way more often then you think.
It clearly depends on the type of product, but generally speaking, you should be spend mosting of your money on making the product as self-serve as possible. An online self-serve model is the model which will grow fastest, so do that rather than designing for a requirement of human involvement in the sales process. Inside sales to convert trials, coaching of users, webinars to accelerate conversion - sure. But design around self-serve automation as much as you can.