When should I send surveys to backers?
You should wait 14 days after your crowdfunding campaign ends before sending out surveys. Kickstarter and Indiegogo take approximately 14 days to finish processing payments and allowing backers with failed payments a chance to update their method of payment.
After the 14 days, your crowdfunding site should send you your payments and you'll see which backers haven’t yet paid. Backers who don't complete their payment on your crowdfunding site are imported to BackerKit and their payment is marked as 'failed'.