You're getting your days and nights mixed up. It's the nights you're short on with your Friday/Sunday tradition.
that’s the whole point, there aren’t “days” and “nights”.
in the Scriptures, any part of a day or night is counted as a whole day.
a baby born one minute before sunset and dies one minute after sunset, lived for two minutes, but according to the SCRIPTURES, was alive two days.
your scenario conveniently ignores the “day” of the 14th of aviv, which is required or else you would have 4 days and 3 nights in the heart of the earth.
misinterpreting Matthew 12:40 causes all kinds of problems, doesn’t it?