Garmin/GPX files: Day 1 | Day 2 morning, arvo | Day 3 morning, arvo
The Greenstone/Caples track is normally done over four days, as outlined in the DOC info above. If you were doing it over four days, I'd recommend using the DOC huts, and it's handy if you're coming from far away as there's a short first and last day (if starting from Greenstone carpark).
I've outlined the timings below. As you can see, I'm not exactly a speed demon - my fitness doing this is poor, I was slow on the uphills, and I regularly stop for 5-10 minutes to take photos. I also have little legs. Basically, if I can do this, so can you.
Garmin/GPX files: Day 1 | Day 2 morning, arvo | Day 3 morning, arvo
Day 1 GPX file | 16.25km, 5 hours activity, 3.5 hours moving
Day 2 morning, arvo | 30.11km, 9 hours 50 minutes of activity, 6 hours 10 min of moving per Garmin
Day 3 GPX morning, arvo | 17km, 5 hours 10 minutes activity time, 3 hours 45 minutes moving time