day one

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day one

The first day or the beginning of something. Honestly, I've loved Frank since day one, long before we officially started dating. I'm sorry, but your assistant has annoyed me from day one. How can you stand her constant cheerfulness?
See also: one

*day one

the very beginning; the very first day. (*Typically: from ~; since ~.) You haven't done anything right since day one! You're fired! She was unhappy with her new car from day one.
See also: one

day one

n. the first day. (Often with since.) You haven’t done anything right since day one! You’re fired!
See also: one
References in periodicals archive ?
So you must complete the 14-day assessment with an ARD of day 1 through 19 to set payment for day 15 through 30.