Yes, I have had two Aunts and my best friend’s mother and their symptoms appeared slowly. There are 7 stages of the disease, in some cases they come on quickly, in other cases the progression is slow. I have read extensively on the subject when my Aunt was diagnosed and took a class with my friend when her mother was diagnosed. I am no expert, but I do know the disease affects people differently. My Aunt was hostile, agitated. My friends mother is very sweet and childlike. Your one size fits all is incorrect, your fathers symptoms may have been sudden and obvious, but that isn’t the case with everyone.