This isn't an idiom. It means just what it seems to mean. Something is only a matter of time - you only have to wait until it happens.
The meaning is that it is the right time to do something.
If something is beyond all question then there is no chance that it is wrong.
That's not an idiom, it's just a statement. Someone is saying they got no response to a question or action.
Having fun;Great time
It's not an idiom - it means just what it says. Something took "no" time to come about. It's an exaggeration, but the meaning is plain.
The idiom 'sands of time' refers to the inexorable forward movement of time. It refers directly to the sand running through an hourglass.
The idiom you have alluded to means to be placed precariously or unfavourably in a situation. The American expression "skating on thin ice" has a meaning that is synonymous and can be used interchangeably with the idiom in question.
The idiom 'on the dot' means at a precise time or right on time.
It means precisely at that time - no earlier or later.
"To be" is not an idiom - it's a verb.
Anything that is NOT a phrase whose meaning is not clear is NOT an idiom. This is a confusing question, because a tortoise is not an idiom. I'm not sure exactly what you're wanting here.
Please ask one question at a time.