I used to believe that was a proper way to proceed. I really don't anymore. Are we to act like everything is okay for an entire life time hoping that someday they'll somehow realize that maybe that lifestyle isn't.... in the hope that when they do they'll think of one of us to talk too? I don't believe that anymore.
Honestly, I lean toward the principle of when one won't accept your grace, (your message of the Christ and his salvation)... that you shake the dust from your sandals and move on to someone who might recognize the need for a savior. Tough words I know, but we are in a country that is moving away from God. Acting like that isn't a problem so that we maintain "contact" with them in hopes of a conversation some day.... I dunno.
I think it depends on the relationship. Oscar Wilde converted to Christianity on his deathbed because he had a lifelong friend who knew enough about Wilde to know that was the way to play it.
Other people, other friendships, I’d say be open to whether the Spirit is moving you to say something directly and promptly.