I think it should be noted that
*Ich arbeite nicht morgen
is a borderline case of incorrect word order. Yes, this word order could be met out there in the wild, but you need very specific context to make that occur.
Actually this word order is plausible only when understood as en ellipsis, and the left-out part gives actual information why morgen is not correct, e.g. "ich arbeite übermorgen". This could happen in a conversation like this:
Fritz: He Klaus, du hast doch gesagt, morgen gehst du zur Arbeit. Kannst du mir den großen Schraubenschlüssel von da mitbringen?
Klaus: Ich arbeit nicht morgen, [ich arbeite übermorgen].
In any other situation, "Ich arbeite nicht morgen" seems implausible to me. You would say:
Morgen arbeite ich nicht.
Ich arbeite morgen nicht.
There is another scenario where "Ich arbeite nicht morgen" could be met: that's actually when the speaker has insufficient command of German - e.g. having learnt German just recently, or living in an immigrant community using alternative forms of German.
And a last one: In very sloppy everday German you may say "Ich arbeite nicht morgen" in a way of post-factum adding the "morgen" for clarification. But this should rather be written like
Ich arbeite nicht, morgen.
because a native German speaker would at least feel that the word order is incorrect, and that "morgen" is added for precision when the sentence actually has already finished.
I would not recommend this in a textbook on German for beginners. It leads people in a wrong direction.