The IRS will begin processing 2017 efiled returns today January 29.  There are many stockpiled returns that have been efiled during January and have been "pending" for several days.  So it will depend on "how soon" the IRS pulls your return for processing as to how much longer it will be "pending."

Normally it takes 24-48 hours for a return to go from "pending" to either accepted/rejected.  But in the first couple of days when the IRS starts up today, no one knows for sure yet.

You can also monitor the status of your efiled return by logging back into your account or checking with this tool:
https://shop.turbotax.intuit.com/efile/efile_status_lookup.jsp

Once your efiled return is accepted, you can monitor the Federal refund status at this IRS website.  It can take up to 24 hours after acceptance before it starts showing up here:
http://www.irs.gov/Refunds

To track a state refund:
https://ttlc.intuit.com/questions/1899433-how-do-i-track-my-state-refund

This is an update to mesquitebean's information for the 2019 tax year.

 

The IRS began processing returns on January 27, 2020.   You can go to Check on your e-file status today and sign into your TurboTax account to get your update.  You can also go directly to the IRS at Get Refund Status. 

 

For your state tax refund status, go to How do I track my state refund?