To really trust my individual T, to share certain things I've never shared with anyone, probably close to 3 years for me, too!

For my marriage counselor, maybe a year to a year and a half? He discloses a lot more about himself, including some issues he's had with anxiety, so it made me trust him more quickly. (T doesn't share much.) What also helped was discussing my transference with him and having him accept it and help me work through it helped--though led to a bit of a rupture at one point. But then we worked through that, which led ultimately me to trust him more.