How long is an 'OK' length of time at a place of work?

[Autumnleavesandhotchocolate]

I started a new job last month. It was an impulsive decision to leave my last place of work (where I had been for over 8 years - I do not make a habit swapping and changing jobs) and the 'on boarding' process at the new place has been frankly none existent.
It was a mistake. I am hugely unhappy. I have never cried as much in my entire adult life as I have during the past few weeks. My hair is falling out, my skin is a state, I can do the actual job, it's the same as I was doing before, just slightly different systems and processes. So it isn't as though I have talked myself into a job out of my league. I just genuinely don't think I'm a fit for this particular place.
The way I feel at the minute, I don't think I can stay there long term. However I know a short term blot on a CV will not look good so I was wondering, how short a stay is considered to be an OK amount of time to have spent in a work place?
To be clear, I work hard, do not have time off and am friendly and polite, I would like to think my references would reflect this and would not have anything negative to say - other than potentially the short stay....

@ABrotherWhoLooksLikeHellMugYou FTCs are different, obviously!

I stayed in an awful Jon for a year just so it wouldn't look bad on my CV but I should have just left it's not worth it

Generally, I’d say a year. However, as you’ve got 8 years at your previous job you’ve shown you can be committed so I wouldn’t worry about it. Certainly if it’s making you that unhappy you should get out as soon as you can, just do everything you can to make sure the job you jump to is a good fit so you can stay there long enough to make clear that this one short job was a blip rather than a pattern.

But why are you unhappy? It's only a month. Adjustment takes time. Change can be hard to
Manage

Give it time. Find your tribe