Is it proper grammar to say on today and on tomorrow? WIthin the context of this dialect, the formation "on today" and "on yesterday" would be considered correct by those speakers, or they wouldn't be saying it that way However (and I cannot back this up with a citation), in general, most English speakers in the US would not use "on" before "today" or "tomorrow "
Today Was vs Today Is - English Language Usage Stack Exchange Today means "the current day", so if you're asking what day of the week it is, it can only be in present tense, since it's still that day for the whole 24 hours In other contexts, it's okay to say, for example, "Today has been a nice day" nearer the end of the day, when the events that made it a nice day are finished (or at least, nearly so)
Which is correct? . . . . . as from today or from today onwards Two other options (in addition to "as from today," "from today," and "effective today") are "beginning today" and "as of today " These may be more U S -idiomatic forms than British-idiomatic forms (the two "from" options have a British English sound to me, although "effective today" does not); but all five options are grammatically faultless, I
history - Change from to-day to today - English Language Usage Stack . . . today O E todæge, to dæge "on (the) day," from to "at, on" (see to) + dæge, dative of dæg "day" (see day) Generally written as two words until 16c , after which it usually was written to-day until early 20c Similar constructions exist in other Germanic languages (cf Du van daag "from-day," Dan , Swed i dag "in day")
Grammatical term for words like yesterday, today, tomorrow The Cambridge Grammar of the English Language, would consider words like yesterday, today, tonight, and tomorrow as pronouns (specifically, deictic temporal pronouns) Related info is in CGEL pages 429, 564-5 –
Calendario