Not a specific answer as there is no reason for 1040-ES not to be final. But if that's all you're waiting for you can print the forms from the IRS website as they have final forms there. No need to hold up a return for something minor. OR let the client know you will mail out the forms when they are available.

The reality is, because mail sucks so bad I'm trying to get all my clients to pay online and get a printed confirmation. I even created a page reflecting every states payment website to make it easier for them.