I don’t think there’s a time but you’ll probably truly love a person when you have known about the person well enough; what makes them happy, what makes them sad, their dreams, ambitions, likes, dislikes, their past relationships, their hobbies etc. Love isn’t always about happiness and sweet things. You have to make sure you will be their rock to tide through difficult times. That means that even when they push you away, even when they are angry or frustrated, you will not let go nor will you give up and get angry. You have to make sure you will be there no matter what because right beneath all that anger and frustration is sadness. They’ve been hurt and you have to be there to make sure you can help them get past that phase of their life.
We humans, we are great actors. When you meet someone for the very first time, there are things about themselves they tell you. Things that may not be completely true, things that they tell everyone and things they know people want to hear so that they represent your ideals about them. But there are certain things that they’d tell only you when they don’t mind showing you what a mess they are, when they know that you’d understand how much the rough of life has made them, even if it may not be nice. When that happens you know you’re the one, and they are yours.
But when you have earned their trust, when they let you in to their life, don’t ever abuse that privilege. Don’t ever use their weakness against them, don’t be that hurtful person whom they try very hard to stay away from. Be sure to embrace their insufficiencies because when you do, you will be loved by the one you love the most even if the world is against you.