How long do you keep foundlings separated?

My husband rushed in the door about an hour ago and handed me a cat.  He was supposed to be at work.  He basically said, "My co-workers found this cat.  Anyway, gotta go!" and ran back out the door.  

Currently, the little fella is in my bedroom, with a fresh litter box, food, water, bed, and hasn't come into contact with any of my cats.  My kittens haven't had their full set of vaccines yet (just the first set).  I have all kinds of wormers and topical flea/earmite/worm treatment on hand, so I gave him that, since he has a pot belly and gunky ears.  

This is the first time I've had a cat come into my home so suddenly, so I'm wondering if you guys just keep strays separated forever until they find homes or until they've been to the vet, or... what?  Other than the worms and ear mites, he seems perfectly healthy.  

Until he's been tested for FeLV/FIV and cleared by the vet.

The strategies differ,  save the necessary deworming and check up.

If you have pure indoor cats, perhaps with some health problems, or are a breeder - verry strickt quarantine and all other precautions.  Which may mean, the rescue often never mets the residents.

Or if your cats are themselves rescued ex homeless, or healthy cats used to roam outside - here many owners dont make big fuss, and let them meet immediately after deworming is fully done, and the vet check up.

I suspect some even without the vet check up...

Most are somewhere in between, depending on circumstances, and your feelings and need of security.

Good luck!.

Definitely keep the stray separate from your kitties until cleared by the vet. Also wash your hands after interacting with the stray before touching your cats.

If I'm planning to rehome a stray, I don't introduce it to my cats at all. They may not get along and it's not worth the effort if I'm not keeping the stray.

If you plan on keeping it, I wait until the vet has cleared him or her and usually until the stray has been fixed, too. It's usually a few weeks before I introduce.

And I usually start with letting them see each other before I let them interact. I put a baby gate up in the door between them.

It's worked for me several times! Good luck!