Using "present perfect" for things that happen in future

Solution 1:

It’s unhelpful to think of the present perfect construction solely in terms of past time. It is used in talking about the future following when, after, as soon as and until.

Solution 2:

In a narrative, a succession of events is described. Most often, the events are cast in the past tense:
- This happened.
- Then this happened.
- Then this happened.

But they may also be cast in the present tense (the so-called ‘historical present’):
- This happens.
- Then this happens.
- Then this happens.

Note that in the latter example, it is clear that the ‘speech time’ is repeatedly moved forward, so that it always coincides with the ‘event time’. (Some formal grammars use the term ‘reference time’ to name this moving ‘speech time’ and distinguish it from the actual time when you are speaking—or, in written utterances, when you are read.)

Exactly the same thing happens when you tell someone to perform a sequence of actions, which is expressed using the imperative mood, unmarked for tense:
- Do this.
- Then do this.
- Then do this.

In effect, the ‘Thens’ keep moving your ‘speech time’ forward to coincide with the ‘events’.

In your example, When Adobe Shockwave Player has finished installing plays the role of ‘Then’: it shifts your ‘speech time’ into the future, and defines how you may recognize that you have reached that time.