There are only two options thank goodness
1) OP was wearing his legs the whole time because they never went to bed. He chose to lie about this because the original prosecution case used OP putting on his legs prior to going to the toilet with his loaded gun to bolster their claim of premeditation. Works b/c Prosthetics 'on' isn't or isn't conclusively demonstrated by the evidence. Maybe he was kneeling or crouching, better balance for the latter with prosthetics on.
2) No prosthetics - Heat of the moment, fight with Reeva vs fear of intruder. Slower & going back putting on prosthetics would allow him to add needed minutes to his timeline.
If available or performed the results of these standard Police investigative techniques could have helped better answer these questions. I have no idea if they were or were not performed. If anyone knows, would be great.
- The bases and shafts of both of OP's stumps should have been swabbed for blood and the fronts of stumps for gunshot residue
- Presence of Gunshot residue on the ventral surface, shin surface of the stumps would prove prosthetics were NOT on.
- Presence of Reeva's blood on the base (heel) of his stump would prove he was on stumps.
- Absence of the blood above proves nothing. Could be stumps on clean tile or prosthetics on.
- Test the prosthetics for gunshot residue, if present he wore legs when shooting
Just my thoughts. Might have to draw up a wish list.