I would hesitate to actually get paid up front unless you really do have something coming soon, but it's quite trivial with many of the payment networks to collect the information and not charge until you're ready. If you truly have no product yet and your ability to deliver is not certain, this seems like a reasonable way to get promises to pay for something while still having a way to exit gracefully if you find you can't deliver.
Actually, with Stripe and Amazon they will just hold on to the information and not authorize/charge so you can wait much longer (like Kickstarter). The downside is that you aren't guaranteed to be able to charge the amount at the end, but I don't think that's likely to account for the majority of your customers.
