People will be people. It's impossible not to have a first impression. It's impossible not to think something. New experiences, like seeing new people, but similarly other things like a meal, a building, a place,... we always think something. The important aspect is indeed not to judge and to realize you need enough information to judge. A meal might be very tasty but once they tell you the farmer is not being paid fair for the vegetables that might change your opinion. The same goes for people. Also, there's nothing wrong with changing opinions. But as you say it is more important to be aware of what your opinion is based on before drawing conclusions of it and taking actions based on them. Nice writing!