How long ago did you go to wash room before leaving for the concert?

[tufguy]

How long ago did you go to wash room before leaving for the concert?

How many hours ago did you go to wash room before leaving for the concert?

Please check my sentences.

 

[emsr2d2]

How long before the concert did you go to the washroom?

The grammatical construction above is the one you need but I can't see a connection between going to a washroom (do you mean bathroom/toilet) and going to a concert?

 

[Rover_KE]

Who are you asking this question, and why?

 

[emsr2d2]

Ah, that's what my friends and I call a "squeeze wee"!

 

[jutfrank]

Ah, that's what my friends and I call a "squeeze wee"!

Or a 'strategic' wee.

 

[GoesStation]

This reminds me of a friend's observation, some years ago, that England had a thirty-to-one p ratio. I think the price of public toilets has gone up since then.

 

[GoesStation]

The euphemism 'spend a penny' in BrE originates from the old penny (£0.004167) you had to put in the slot to unlock a cubicle in public lavatories.

In simple terms then, the pre-decimalization d ratio in Britain was one to one.

 

[Rover_KE]

I think Queen Victoria called it 'the royal wee'.

 

[tufguy]

How long before the concert did you go to the washroom?

The grammatical construction above is the one you need but I can't see a connection between going to a washroom (do you mean bathroom/toilet) and going to a concert?

Yes.

Can't we use "how many hours ago"?

 

[emsr2d2]

You can't use "ago" in the sentence you suggested (with the part about "before you went to the concert").

How many hours ago did you go to the bathroom?
How many hours before the concert did you go to the bathroom?

The second is the best I can do with your original but it's not natural.