Hello, Nellie and thanks for your question.
If you are leaving in four days, you should have your tickets and boarding pass already, if you made your reservations online, and you would see if it says 'TSA Precheck' on those, or has your KTN (Known Traveler Number) on your boarding pass.
If you are picking up your tickets/boarding pass at the airport, you can call your airline, United, to see if the KTN is on your travel documents. Their number is: (800) 864- 8331 If it is not, you can ask them to add it.
If you enrolled in the TSA Precheck program, there is no guarantee that you will receive it on every flight. It is a randomized system and every registered passenger will not receive it all the time, to increase security measures.
You can call the Universal Enrollment Center (if United Airlines can't tell you) to ask if you have received Precheck on your upcoming flight. Here is their number and hours:
855- 347- 8371 Hours: 8am - 10pm Eastern time, Mon. - Fri.
I hope this helped!
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