How to know when it’s time for facility placement?

If you are the caregiver that is kind of up to YOU, isn't it? I suspect you DO know, if you are asking the question.
Say more..................

My mother moved to independent living / assisted living this summer. She is 90. The decision was hurried. Pressure from the realtor. And so on. She was offered other options but didn't consider them. But it's her money. So the house is gone and she lost quite a few belongings in the process.
I sense that the management there is simply waiting until she does something such as falling yet again so that they can demand that she vacate her apartment and move in a room at double or triple the cost.

We offered her our home. Or something nearby. No. Not even a better yet cheaper facility would suffice.

The owners are simply waiting.

I do wish she could have remained in her own home but she threw a fit when I suggested care 4 hours per day. But that would have been far better. I think. I know.

Now she begs for rides. It's just ridiculous. And for the money- it's insane.

When you have to ask the question.

When the elder is no longer safe at home, or requires too many people/services to orbit around them daily to keep them in the home and they cannot pay for or organize/manage the people/services, or the caregiver no longer wishes to do it for any reason, all of which are valid.

When home care is no longer safe to do 24/7.
When home care is no longer possible for the person/s in the home doing the care without impacting their own lives to an extreme degree.
This is a matter of choice and safety and a very individual decision.
Most people wait, imho, far too long.