Do you know what species? I've definitely had oysters I've left too long look like that and then still fruited fine. Certain other species I might be worried about.
How to do they smell? Earthy and/or mushroomy? That's good. If it's yeasty, sour, or otherwise bad smelling, then maybe I'd be worried.
But otherwise, get to it. They're ready to go.
The first time I grew oysters, I drilled holes in a 5 gallon bucket, and used aspen shavings from the pet store. But straw and a basket would work too.
I don't remember exactly what instructions I followed, but it might have been https://freshcap.com/blogs/growing/bucket-grow or https://northspore.com/blogs/the-black-trumpet/growing-mushrooms-in-buckets-containers
Good luck! I'm not an expert by any means, but I do have several grows under my belt. Feel free to ping me if you have questions along the way.