When people go into nursing homes it's not always just age but more of the persons health.
Some people can have bad enough health as early as 40 to 50 and go into a nursing home but most people go into nursing homes once they're 80 to 85 years old depending on there health.
Some people live out there full lives in their own home even from their 90s and onward.
However most residents in nursing homes are at least 85 years old or older which is when some people need nursing home care.
But just because you're 80 or 85 doesn't mean you'll need a nursing home as it depends on your health.