Albert Barnes on Titus 1:3

But hath in due times. At the proper time; the time which he had intended; the best time. 1Timm 2:6. Comp. Mt 2:2.

Manifested his word through preaching. 2Ti 1:10. The meaning here is, that he has made known his eternal purpose through the preaching of the gospel. Comp. Rom 10:14,15.

Which is committed unto me. Not exclusively, but in common with others. 2Ti 1:11.

According to the commandment of God our Saviour. Paul always claimed to be divinely commissioned, and affirmed that he was engaged in the work of preaching by the authority of God. See Gal 1:1-11,12, 1Cor 1:1 Rom 1:1-4.