I'm a software developer and co-founder of a start up that's in a sprint to launch a web app the next 2 months. We have about 3 months of burn time we have before we need to get some funding. By that time, we want to have a product with active users, and ideally some revenue. I'm fairly confident that I can accomplish the task by myself, but I have also never launched a project of this magnitude. The better product we can build in this timespan, the faster we can grow our user base, and the better our fundraising options will be. So I'm looking to bring someone onboard to hack with me. Maybe more than one person.

Good help is hard to find, as we all know, and while I'm willing to share equity, I also want that to be contingent on a productive fit. What is the best approach to a trial-type framework for hiring another developer? Something where the other person feels that their work will be rewarded if they do well and that they can't be left empty-handed at my whim, but where I know that if it turns out not to be a good fit, I can pull the cord without significant loss?