I think the puzzle Rolf was wondering about was the ordering of the steps in between Step 1 "I'm going to start something" and Step N "Approach investor". Do you want "Get co-founder" to be step 2 (before you're even sure what the idea is and who you should be looking for) or step N-1 (when you know a lot more from steps 2, 3, .... N-3, N-2 but still don't know how hard the co-founder step will actually be)?

If it's purely a matter of signaling to the investors then you'd think that later would be OK. If it's a matter of learning something important about yourself then maybe the co-founder step should be earlier so you don't accidentally waste your time on something you weren't cut out for anyway... unless we hypothesize some sort of bozo-curing self-cultivation that could be performed?

And in the meantime, because this is reality rather than a thought experiment, there is the complicating factor of the value of the co-founder in themselves, bringing expertise and more hands and someone to commiserate/celebrate with and so on.