How do you know when a person is ready for assisted living?

My Mom is 69, and was recently diagnosed with dementia, possibly Alzheimer's (we are waiting to talk to the neurologist to see what they think it is). I've known she had it for a long time, but we finally got in and did the official testing. She is living on her own in a 55+ community and has a "helper" for activities, getting groceries, etc. She otherwise does fine on her own, but often feels lonely and secluded and if her helper isn't around she doesn't join in many of the activities because her vision is so bad she can't see the sign-up sheets.

I've looked at a few assisted living facilities that look nice, and meet all of her needs, but the average age is about 20 years older than my Mom. When I view the residents in the dining room they just seem so much older, and the row of walkers lined up makes me feel like my Mom wouldn't fit in. But, since she is not cognitively 69 anymore would she notice? The idea of her having all of her meals taken care of, being checked on twice a day, and taken to activities is very appealing. I can imagine the sense of peace knowing she is taken care of in all the necessary ways so that I could just be her daughter and come by to visit for fun instead of care.

How do I convince her of the benefits of assisted living? It's only come up once, and she said "I do NOT want to be put in some home."

Thanks for your advice!