(a)until the day when He was taken up to heaven, after He had by the (b)Holy Spirit (c)given orders to the apostles whom He had chosen.
v.2 (b)Jesus was given the full measure of the Holy Spirit, and thru this in-dwelling of the Spirit, Jesus was one with the Father. Jesus said only what He heard His Father say, and He only did what He saw His Father do. He did everything by the power of the Holy Spirit. Jesus even said “I can do nothing of Myself, but the Father that dwells within Me, He does the works,” Jn 5:19, 30, 8:26, 28, 12:49-50, 14:10, 24.
Luke makes reference to this oneness that Jesus had with the Father when he says He gave orders and chose the apostles by the Holy Spirit.
v.2 (c)given orders- three times, after the resurrection, Jesus gave orders to His apostles. Twice to preach the gospel to the world, Matt 28:19, Mk 16:15, and once, which I believe, He is referring here to “stay in the city until you are clothed with the power from on high,” Lk 24:49. This was the order Luke was referring to; the first order of business, to receive the promise of the Holy Spirit.
Without the Holy Spirit, there is no preaching the gospel to the world. Notice the difference in behavior of the apostles before and after the in-dwelling of the Spirit. Compare the two events; after Jesus was resurrected and presented Himself to His disciples, He told them to meet Him in Galilee. The apostles did as He said, but they were lost and had no direction from the Spirit because they had not yet been empowered with the Spirit.
When they arrived in Galilee, the only thing they thought to do was to go back to fishing, Jn 21:3. But now compare their actions after they receive the Holy Spirit. Immediately they start prophesying and Peter preaches a marvelous and Spirit filled message that leads three thousand people to Jesus in one day, Acts 2:37-41.