First, verify your return was accepted by the IRS - e-file status lookup tool. If your return was accepted less than 21 days ago, hang in there. It can take anywhere from a few days to 3 weeks to go from acceptance to approval.
The IRS issues most refunds in about 21 days, although some returns take more time to review. For the most up to date information on your refund, you can track your federal refund here: Where's My Refund? which provides your current status and a specific, personalized date for your tax refund. You may also download the IRS2Go app to check your Federal refund status.
Here is the general timeline of e-filed returns:
Transmission > Acceptance > Processing > Approval > Refund.
If it has been more than 21 days please see the TurboTax FAQ for additional information, why it may be taking a bit longer to process:
Why do some refunds take longer than others?