This period begins at Christ’s resurrection, includes the present day and will conclude at the end of the world. No one knows when this time span, also known as the ‘day of grace’ will suddenly finish. The implication is: don’t put off turning to Christ. When under conviction of the Holy Spirit to receive Christ, do not put it off until a more convenient time; you may never have another chance, so “Today, if you hear His voice”, respond by repenting of your sin and accept the offer of salvation (Act 24:25; Heb 3:7-11).
How can I be a brighter light or saltier salt?
Christ the "light of the world" (Mt 5:13-16; Jn 8:12, 9:5; 2 Tim 3:1-5).