It’s too late to go shopping. The shops are open only until 5:30. They will be closed by now.
Yes, closed here is employed as an adjective. You are correct in understanding it to designate a state rather than an event.
And it is true that the expression by TIME is used with events rather than states—as your source says, it says that something ‘happens’ (an event) rather than ‘continues’ (a state).
HOWEVER: The expression by TIME does not compel you to employ an ‘eventive’ predicate or forbid you to use a ‘stative’ predicate. In fact, the compulsion works in the opposite direction: when you use by TIME, you compel your hearer to understand the predicate in an eventive sense. With by TIME the hearer interprets a stative predicate as the result of a change of state: something happened before TIME to bring about the state you describe.
Here are examples of by TIME with three stative verbs, know, own, be:
By April he knew that the operation was a failure. ... implies that he did not know this earlier, but at some time before April he learned that the operation was a failure
By 1973 he owned 26 newspapers. ... implies that he did not own so many newspapers earlier, but at some time before 1973 he acquired 26 newspapers
By next week you will be in Toronto. ... implies that you are not in Toronto now, but at some time before next week you will go to Toronto
In the same way, The shops will be closed by now implies that earlier the shops were open, but at some time before now the shops were closed. Since it is explicitly stated that the shops are open until 5:30, we understand that this sentence must have been uttered at some time after 5:30.
The word will may have caused you some confusion. This will does not designate some time in the future; it expresses a certain inference in the present. (Linguists call this ‘epistemic’ will.) Your last sentence may be paraphrased
It is certain that they are closed by now.
Wait a minute
This is pretty generic and informal and is often used idiomatically to ask someone to pause what they're doing until told to continue. It doesn't usually mean exactly a minute, any more than "wait a second" means exactly a second.
Wait for a minute
This sounds like something that you'd find in directions/instructions:
Wait for a minute and then add the oil to the pan.
In this case, it more often means exactly a minute, though it's not required. The exact timing here is more important. You would be unlikely to find native speakers who would use this in the idiomatic manner of the previous example.
Now, does this carry over to numbers of minutes greater than one? Sort of?
Wait five minutes
Will usually mean five actual minutes... otherwise, why bother specifying the number. As mentioned before, "wait a minute" doesn't really mean a minute... one could end up waiting for a few seconds or several minutes in the end. Even in directions, you'll often find they've left out the "for" in this case:
"Remove from stove after one minute of boiling and wait five minutes before topping with granola."
So what about with the "for"?
Wait for five minutes
This isn't wrong. Using it this way is not ungrammatical at all, it's your choice. It's not required and you will definitely find examples of it, particularly in more professionally-written instructions:
Slide the whole skillet under the broiler, and wait for five minutes, until the crumbs are golden brown and the salmon is done.
This is also discussed, though not to a great degree, in Cambridge Dictionaries Online:
Wait means ‘stay in the same place or not do something until something else happens’. We can use it with or without for:
- Put a tea bag into the cup, then add water and wait (for) a minute or two before taking it out.
- I phoned the head office but I had to wait (for) five minutes before I spoke to anyone.
Best Answer
Either "for" or "until" would be idiomatic in both your examples. "Until" is slightly more pedantically correct, but a native speaker would understand either, and might use either (or the abbreviated "'til", dropping the "un-"). For most purposes, they mean the same thing in this context. The reason "until" is slightly more correct is that "tomorrow" is (in this context) acting as a time, rather than an object (for the arrival of which you might wait) or an event (for the occurrence of which you might wait).
In some slightly modified examples, "for" and "until" would still mean the same thing, but would need you to phrase the sentence differently:
However, as a side note, your examples probably do not mean what you think they mean. "You can better wait until tomorrow" means that you are better able (than something or someone else implied by context) to wait until tomorrow. Normally we would say "You had better wait until tomorrow".