How long will it take to receive notice if my extension was accepted?

[michaelr]

I made an error entering my estimated tax liability for 2018, will my extension still be considered?

[Harnika · Accepted solution]

If you filed your extension electronically using TurboTax, you'll receive emails updating you on the acceptance status with the IRS. 

[JohnW15]

When you e-file your federal tax return extension using TurboTax, you'll get an email confirmation letting you know if it was accepted or rejected, usually within 48 hours.

Yes, your extension should be fine -- you only provided an estimate, anyway.