You can check your extension status when you log back into TurboTax, should say right on that first screen. As long as you filed for the extension in TurboTax Easy Extension online you should receive an email confirmation within 48 hours.
You can also check by using this TurboTax website to check the status of an e-filed return or extension and if it was either accepted or rejected - https://turbotax.intuit.com/tax-tools/efile-status-lookup/
For more information about filing extensions, please see the following article:
https://turbotax.intuit.com/tax-tips/tax-extensions/what-to-do-after-youve-filed-an-income-tax-exten....