Jhn 17:4 I have glorified thee on the earth: I have finished the work which thou gavest me to do.
I represented you on the earth, bringing the work to completion which you have given me in order that I will make ready.
This verse seems to be saying a great deal more than the KJV translation. The KJV simply say that Christ has completed his work, but the original Greek seems to say that this work related to something that needs to be done in the future.
The last verb, poieô, has many different shades of meaning, but it basically means "to make" or "to produce." The problem is that this verb is shown in the future tense. Christ is saying that he will do or make or produce something in the future. In other words, Christ's mission on earth was not an end to itself, but preparation for something more that Christ will do in the future. Does he mean after his death and resurrection? Possibly.
The context may suggest that he is referring to the creation of "life lasting age" when we can learn to know God and Christ (Jhn 17:3). However, using the larger context of the section, he may be referring to making the connection to the Holy Spirit.
ἐδόξασα (1st sg aor ind act) "Glorify" is from doxazo (doxazo), which primarily means "to think", "to imagine," or "to suppose." Secondarily, it means "to magnify" or "to extol," which is where we get the "glorify" used in the translation.
τελειώσας (part sg aor act masc nom "I have finished" is from teleioo, which means "to make perfect", "to compete", "to bring to consummation," and "to bring fruit to maturity."
ὃ "Which" is from hos (hos), which is the demonstrative pronoun in its various forms (hê, ho, gen. hou, hês, hou, etc. ; dat. pl. hois, hais, hois, etc. gen. hoou). It means "this", "that", "he", "she", "which", "what", "who", "whosoever", "where", "for which reason," and many similar meanings.
ποιήσω (1st sg fut ind act) "Do" is from poieô ( poieo), which means "to make", "to produce", "to create", "to bring into existence", "to bring about", "to cause", "to render", "to consider", "to prepare", "to make ready," and "to do."