Saving progress on a form before signing

I work for an organization that runs programs and requires an application be filled out and signed by potential participants. We're trying to convert to using electornic signatures using the eSign service, however, the application has 30 required fields that will probably take 20-30 minutes to complete, as well as 3 signatures spots.

Our concern is that not everyone will want to sit down and complete the form in one go (it's a fairly exhaustive application), but they may wish to save their progress and return to complete the form later. Is it possible to save progress with eSign? I don't see the option when I've sent the form to myself for testing. If form progress can't be saved, do you know if the window will time out, or can the window be left open indefinitely until they're ready to complete the form?

Thanks for any help