Acts 1:7
Jesus replied, "You are not permitted to know the [specific] time or date [when this will happen]. For the Father has appointed it [to happen] when He determines [the right time].
Acts 17:31
For He has appointed a [certain] day when He will judge the people of the world according to [a standard of] true justice by the man [i.e., Jesus] whom He has appointed [as Judge, See II Tim. 4:8]. [And] He has given assurance to all people [that He will do this] by raising Jesus from the dead."
1 Thessalonians 5:1
Now brothers, you do not need to have anything written to you about the times and dates [i.e., of Christ's second coming],