Average Data Usage

[Curisu]

I once was in the same situation and used my 4g to play for a month.
I did everything as normal, savage raids, discord, etc.
The only thing I remember was that a full eureka instance (144 player) needed about 300-500MB per hour.

Everything else was not really noticeable.
I used in that month about 25gb data for FFxiv alone and most of it was due to eureka.

Also, at the end I was able to raid in 8 player groups with reduced data speed.

To mention is also that I got 100gb for free, so I was really wasteful.