You're splitting hairs
72 hours = 24 hours x 3 days (same difference)
No, it's not the same thing.
For example, if you plan to arrive on the 5th at 1 PM, "3 days before" would mean you can fill out the TDAC all day on the 2nd, whereas "72 hours before" means you can only fill it out starting at 1 PM on the 2nd for it to be valid.
The Thai Embassy clearly states in red "within 72 hours before entering Thailand."
http://www.thaiembassy.fr/fr/visa-rdv/infos-generales/thailand-digital-arrival-card-tdac/Hi,
I did a simulation of the TDAC with my details.
When you get to the arrival date section, a table opens where you can indicate your arrival day.
However, only 3 days are available.
For example:
I fill out my TDAC on August 6th, I can indicate my arrival day up to August 9th, but not beyond.
Exactly, the Thai Embassy in Paris states it must be done 72 hours before arrival.
Assumption:
A flight from CDG lands at 9:00 AM on Thursday, September 18, 2025, in BKK (3:00 AM Paris time).
So, following the logic,
You can fill out your TDAC starting from Monday, September 15, 2025, at 4:00 AM (Paris time).