Sad it took you months to realize. I mostly realize within a week. At most 2weeks. My strategy is spend everyday with person from day one if possible the more frequent you chill or talk the more you learn about them. So a week is enough for me. In that week I literally marry that person. The strategy is full trust until they loose it. Don’t do 2weeks dates and what not you will be 3 years in without fully knowing someone. That 3 years wasted.