[otoburb]

If you are currently unable to find a business development co-founder, and you are asking for assistance to find potential candidates, a goal-oriented environment or social mixer(s) sponsored by an accelerator/incubator may bear fruit regardless of whether you actually apply or go through with a program.

In other words, I'm thinking more of the peripheral social benefits (where "social" here means "expose oneself to possible business development co-founder candidates") than the actual programs themselves. Since it doesn't sound like you are sure what traits to look for, even if such a course of action doesn't turn up a good candidate, one hopes that you'll end up with a better idea at the end of the process; possibly worth putting aside the pessimism.

If you're feeling plucky or feel the opportunity cost of the search will be too great to bear due to a massive loss of momentum, you will probably need to try it alone for now to get a feel for the exact skillset a candidate could bring to the table.