John 15:2 Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit.

Every Christian begins bearing fruit right from the moment of new birth. This is fruit of the Spirit not of the person.  Even immature Christians bear fruit.

When Christians try to bear their own fruit, they no longer are abiding in the Vine, Jesus.  They stop bearing the fruit of the Spirit.  They may do a lot of work, but it is their own work.  Jesus wants to do His work through us.  He doesn't want us working independently from Him.