The question is, at what point do people decide that they want to age-in-place or remain in their current home? Is this a conscious decision that happens relatively early on in life - say one someone is in their 50s - or is it an evolving decision that maybe is never actually thought out or verbalized but just sort of happens?
Is deciding to age-in-place a life benchmark such as trying out for Little League, graduating from high school, getting that first real job, or purchasing that first really nice car (new or a used one in nearly-new condition)? Is it more voting against going to a nursing home rather than consciously choosing to stay at home, or is it a definitive choice to declare the current home as the forever home and to remain there - essentially at all costs?
Do people actively look for and select a home as they go through life that appeals to them so much that they declare to themselves that this is the home they want to grow old in - that they don't need or desire to find another home after this one?
Or, do people at some point just figure out that this is a home that meets their needs and that they do not need to look for another home? Maybe they never actually admit it out loud. They just know that the home they have appeals to them.
Maybe nothing at all happens. There is no conscious effort to locate a home that they want to remain in, there is no admission that this is the home that will be their forever home, and there is no thought about it being that special time. Somewhere along the way, they simply stop thinking about - or possibly acting upon - the need or possibility of moving from where they are.
Finding a forever home is a little like forming a personal relationship. At the outset, someone might know (or feel very strongly) that this is the home they have always wanted and that they will not need to think about finding any other one - ever. Someone might know that they have selected the wrong home and commit to keep looking for a home that meets they needs better.
Some might not have a real strong feeling that this is the home they want to remain in, but there is no specific reason for them to sever the relationship either so they keep living in it. One day years later, the come to the realization that they have lived in this home for years and that they essentially have committed to staying there. They didn't set out to do so, but it just happened.
As to when people actually decide to stay in their current home and age-in-place, it is as varied as the people involved. It can happen at the outset of finding a home, it can happen along the way, or it might never happen in a declarative sense but just evolve. Therefore, we need to expect that people will want to remain living in the homes we find them in unless they specifically let us know that this is not the case. Then we can help them make those homes the most suitable for their needs and budget to keep them safe and happy.