Great question — answering as the UphillTech team:
Pretty much by definition, the answer is none . Visas/ETAs etc are required before you board your flight, they're verified at check-in and you'll be denied boarding without one. Digital arrival cards are checked on arrival (surprise!) and can be completed at any time before you arrive at the immigration counter. I've had check-in counters suggest filling them out before arrival, but not having completed it is not going to stop or even slow you down. All that said, I make a point of completing everything before I get to the departure airport. There's no upside to doing it later, and if you wait until the last moment you may run into issues with mobile data/wifi/battery/website down etc.
Full answer by lambshaanxy: https://travel.stackexchange.com/a/204222 (CC BY-SA 4.0).
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