Some commentaries of the early Church fathers on this passage:
Jerome: Having then shewn that the Son of God cannot be ignorant of the day of the consummation, we must now show a cause why He should be said to be ignorant. When after the resurrection He is demanded concerning this day by the Apostles, He answers more openly; “It is not for you to know the times or the seasons which the Father has put in his own power.” (@Ac 1,7@) Wherein He shews that Himself knows, but that it was not expedient for the Apostles to know, that being in uncertainty of the coming of their Judge, they should live every day as though they were to be judged that day.
BAug.,de Trin., i, 12: When He says here, “Knows not,” He means, ‘makes others not to know;’ i.e. He knew not then, so as to tell His disciples; as it was said to Abraham, “Now I know that thou fearest God;” (@Gn 22,19@) i.e. ‘Now have I caused that thou shouldest know,’ because by the temptation he came to know himself.
Aug.,\b Serm., 97, 1: That (p. 833) He says that the “Father knoweth,” implies that in the Father the Son also knows. For what can there be in time which was not made by the Word, seeing that time itself was made by the Word!
Aug.,\b Lib. 83, Quaest. Q60: That the Father alone knows may be well understood in the above-mentioned manner of knowing, that He makes the Son to know; but the Son is said not to know, because be does not make men to know.
Origen:\b Otherwise; So long as the Church which is Christ’s body knows not that day and hour, so long the Son Himself is said not to know that day and hour. The word “know” is used according to its proper usual meaning in Scripture. The Apostle speaks of Christ, as “him who knew no sin,” (@1Co 5,21@) i.e. sinned not. The knowledge of that day and hour the Son reserves in store for the fellow-heirs of the promise, that all may know at once, i.e. in the day when it shall come upon them, “what things God hath prepared for them that love him.” (@1Co 2,9@)