Determining WHEN to take COVID test for return to US

[hoosier2017]

Hello CC family,  I, probably like many of you, am trying to make arrangements for testing to return to the US.  I have read and re-read the United airlines website and the CDC site.   To test, no earlier then 3 days before return….is that from the time of your flight home, day of departure? If I am disembark on Saturday and test on the ship, and leave Switzerland on Tuesday afternoon, are my results “timely”?  I will not be within a 72 hour window.   I have found places to test once off the ship, so I’m not concerned about that, but certainly would be easier to just be done with it prior to disembarking.    
I have to say that in reading posts here (on a daily basis) I’m so happy to see during these crazy times that there are caring people who genuinely want to help others! Thanks, in advance, for the advice.  

[jpalbny]

AFAIK it's three calendar days, not 72 hours. So Saturday should be OK for you.

[loriva]

From the CDC website:  https://www.cdc.gov/coronavirus/2019-ncov/travelers/testing-international-air-travelers.html
--A test result must be in the form of written documentation (paper or electronic copy). The documentation must include:
--Type of test (indicating it is a NAAT or antigen test)
--Entity issuing the result (e.g., laboratory, healthcare entity, or telehealth service)
--Specimen collection date. A negative test result must show the specimen was collected within the 3 days before the flight. A positive test result for documentation of recovery from COVID-19 must show the specimen was collected within the 3 months before the flight.
--Information that identifies the person (full name plus at least one other identifier such as date of birth or passport number)
--Test Result  
Why does the Order specify 3 days rather than 72 hours? What is considered 3 days?
--The 3-day period is the 3 days before the flight’s departure. The Order uses a 3-day timeframe instead of 72 hours to provide more flexibility to the traveler. By using a 3-day window, test validity does not depend on the time of the flight or the time of day that the test was administered.  For example, if a passenger’s flight is at 1pm on a Friday, the passenger could board with a negative test that was taken any time on the prior Tuesday or after.
--Get tested after you get home and quarantine as much as you can.  The CDC recommends doing so for three to five days after returning home.  If you want to be extra safe, get another test 10 days after returning.

[14ersco]

We were in Europe this summer and we waited until 24 hours before our flight home to get the test.  Our logic was that if a test just happen to come back positive at least we would only spend a short period of time in a quarantine instead of losing a number of days of our vacation.  For our next months Europe trip once we arrive in our departure city we will straight away go to the TI to find out the latest testing options to see if anything has changed from what we have gathered on the web. 

[Lois R]

I am flying to Portugal on Wednesday afternoon.🙂  Just got my Antigen test...ALL NEGATIVE👍

I will have my test on the ship on the 19th....get off the ship  on the 20th and I fly home on the 21st.