Shulchan Aruch, OC 489:4 (in my own translation):
Someone whose friend asks him during twilight "How many days of the [omer] count tonight?" should tell him "Yesterday was such-and-such". For if he tells him "Today is such-and-such", he can't go back and count with a [preceding] benediction.
Mishna B'rura :20 (in my own translation):
"'Today is such-and-such'" — and even in a foreign language. But if he didn't say "Today", we have no [concern] about it [i.e. he has certainly not fulfilled his counting obligation and can therefore say a benediction and count], because the main command of counting is that he say "Today is such-and-such".
- Does "Tonight is three days of the omer" (or the equivalent in Hebrew) count as "Today is three days of the omer"?
- Does "Tonight is three nights of the omer" (or the equivalent in Hebrew) count?
- Does "Now is three days of the omer" (or the equivalent in Hebrew) count?
In English, "It's Tuesday." is used to indicate unambiguously (if context doesn't provide another meaning) that today is Tuesday. (Saying "Tuesday" alone is not.) Most likely, though, the "It" in that sentence does not refer to some hidden antecedent "Today".
- Does "It's three days of the omer" count?