The saints are already in the kingdom. Notice the past tense:
Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son: Col 1:13 (KJV)
Our marching orders are to spread the good message; not to rule with a rod of iron. We're to wait for the return of the King for that.
We are in the Kingdom yes, by virtue of our legal relationship. But we are not actually, physically, in God's Kingdom yet. Jesus said the Kingdom is "near" and not yet "here." I don't know what you're waiting for, but I'm waiting for the Kingdom even though I'm already a registered citizen, and quite legal at that!