I think you’ll always have a stronger case for yourself if you have some work to show before asking for money to do more. I think it’s up to you, though. I had only made my pilot before crowdfunding for Brains, which I think helped, and then having a full season helped when I crowdfunded for season 2. But that was largely circumstance and I’m impatient so just making a pilot seems insane to me. I use momentum to do everything and if I’m already making one episode, why not the rest? I’m insane, though, so keep that in mind.
TL;DR- if you have no prior work, making a pilot is super helpful. So it you can make a bomb ass pilot first, definitely do it.