There are 4 to 5 primary symptoms but varies by person. I went to a neurologist . No real predictable signs

There are a lot of possible symptoms, but nobody gets them all. My husband and his brother were both diagnosed at about the same age (80) but have different symptoms. Some are the type of thing you don't really notice at first, like constipation or fatigue or slowing down. Not everyone gets tremors, but people who do usually start on only one side of the body and then it moves to the other. That's usually when people pay attention and ask their doctor. The earliest symptom for some people, from what I've read, is REM Sleep Disorder, where people act out their dreams.