I hope you're having a great day!
Just wanted to confirm that you've completed the [action] you requested. You should expect this to be completed by [date].
Thanks again, and I'll be in touch soon!
Just wanted to confirm that you completed the [action] we talked about earlier.
Thanks for being such a great customer! We look forward to hearing from you soon.
Thank you for completing [the action].
We'll be in touch with you shortly to tell you how to proceed.
We appreciate your time and patience, and we look forward to working with you soon!