* I'm happy to make a quick payment after a first very small milestone (eg a couple hours of work), to build trust that I do pay (I've had this requested by a handful of freelancers and I'm always happy to do it)
* Then, I'm happy to pay weekly at first to build trust, before shifting to every 2 weeks for convenience
If they have an extremely legit web presence, once or twice I've made a small payment up-front, but I don't like doing that. For what it's worth, I've worked with dozens of freelancers outside of freelancing platforms (100+, for a broad spectrum of different roles and projects, if you include platforms, but I'm excluding that because payment is handled by the platform) and I think only 2 or 3 times have I had an upfront payment requested, and I think all 2 or 3 of those were designers. If someone requested up-front payment, there's a decent chance that I would use a different freelancer instead. If it was such a specific service and agency that I had no alternatives, I'd do it, but whenever I have alternatives if it's early on, I haven't yet seen that the work is great, I'm always going to avoid higher effort options and would likely instead use a different provider. It also adds a risk for me that they're going to scam me, and is in my experience rare and atypical, so I'd prefer to avoid it. I'm weird though, I also prefer to avoid doing calls with freelancers until I've worked with them for a little while.
In short, one option would be to break up the payment. Have a first small payment after a day or a half day of work. Request a quick turnaround on that payment (eg same day or next day, if their billing dept can handle that). Then do weekly (with 7 day payment timelines) for a couple weeks. Then shift to every 2 weeks (still with 7 day payment timelines).
General principle: Once someone has sent you at least one payment, the risk is significantly lower that they won't pay you. You're in their system. So, get a small first payment as quickly as possible.
I'd be happy to do that with any freelancer. I think that larger companies may struggle to do that due to their billing department, but perhaps you could do something similar but with Net 30 timelines instead of shorter timelines.
It also makes me think that another option could be to require a $1 up front payment to get started.