It’s not available for everyone yet apparently but @ellie might be able to help in that regard.
I certainly suggest you go over and read the Pay Upfront feature specs very carefully before doing it. Once you use it, you cannot go back and there are people that regret using it who now don’t have a choice.
I have the option but i personally cannot use it because it’s functions do not work well with my project and would screw myself and my patrons over with how it handles people upgrading/changing their pledges (and effectively charging people twice and i have no control over this.) (You can see my feedback and issues with this over at Pay Upfront Flaws & Suggestions - but i know a bunch of people who use the pay upfront feature and it works wonders for their projects! So it really just comes down to making sure it is the thing for you before using it.)