The burger visit (which was with his father) was in Auckland and probably the day before.
Apskip, in general, the assumed date that I use is just for astronomical purposes. It only needs to be within two or three days to make few minutes difference in the shadow positions. So the exact date I use really does not matter for the level of (or lack of) precision that I come up with in my time estimates.
But now that you have opened the date question, let's look at that. As Slowhatch noted, Phil's exact words are
"I've got a little separation between...when the teams get here and when I have to get ahead of them so..."
That says to me that Phil is talking about the time between when teams get to the place where he is and the time when he has to leave to get ahead of them. The place where he is: 'here' in his delivery, probably means New Zealand in general but, in all accuracy, we know that he means the Pit Stop location in particular. And by 'when I have to get ahead of them' he is referring to his need to be at the next Pit Stop location after New Zealand.
With those equivalences in mind I can rewrite what Phil says as:
"I've got a little separation between the time when the teams get to the New Zealand Pit Stop
and when I have to leave for the next Pit Stop
It makes it clear that he is talking about the block of time that starts
when the last of the Teams have checked in to the New Zealand Pit Stop and ends
when he has to leave in order to catch his flight sequence to the next Pit Stop location. We know that the Teams must check into the New Zealand Pit Stop on May 2nd. We do not know when they check in. Where is the proof that the last team checks in at 7:00 pm? Lacking anything solid on last team check in times I would say that Phil's clip very well could have been taken on May 2nd. The next day, May 3rd, would also be consistent with the time time block defined by Phil's statement. However, there is piece of strong evidence in Matt's photo collection that make it impossible for the clip to have been made on May 3rd. Matt took pictures of Phil in the very early (near sunrise) hours of May 4th while Phil was in a boat in the floating village near Siem Reap. And, from my own flight figuring
a few months ago I learned that the best flight sequence from Auckland to Siem Reap on May 3rd left at 4:55 pm and arrived at 7:05 am on the 4th. That best possible flight sequence would not get Phil to the standup in time.
So I think Phil had to have taken an earlier flight sequence than May 3rd 4:55 pm. He may even have made the flight on the evening of the 2nd right after finishing the Bastard Burger.
Bottom line is that, I predict that, this timestamp of 4:05 to 4:45 pm will provide the clue that all Teams have checked in well ahead of 4 pm on May 2nd.
Phil did not have to depart on April 30 from Santiago with the teams. He could have hustled to LaPaz airport after the morning pitstop checkins were complete and caught LAN965 LPB SCL 1245 1745 and gone trans-South Pacific on the night of April 29 arriving early morning on May 1.
No need to speculate on this because we already have a spoiler witness telling us Phil was waiting for his flight on April 29th at VVI.