I can fly Delta Saturday to Friday in March, so I can make the Day 5 test work for both so long as I get the results to give to Delta. If the day 5 folks aren't returning the negative results, that's a problem.Your return test is on the day before you fly; that would be Day 6 of a one-week (7-day) trip.
You get it at one of the four testing sites on Bonaire, or possibly at your resort if they arrange it for you.
Your mandatory Bonaire test is on Day 5, one day too early for a one-week trip.
Your return test only needs to be an antigen test. Your Day 5 test cannot be an antigen test.