Ok, since it's pretty obvious you can't
make a Mythic in 1 day without significant prior work, I figure why not have an actual challenge to complete one in 1 month? That's a fairly generous timeline for anyone with a full time job.
The challenge makes a few assumptions:
1.) You have a level 99 character.
2.) You have access to Aht Urghan.
3.) You're able to get Salvage tags (must have completed Aht Urghan Mission 17).
4.) You already have Captain. If you want a tougher (read: more annoying) experience, feel free to attempt the challenge without starting in Captain status.
5.) You already have the KIs to spam events.
6.) You can do any of the events with friends, solo is not required, i.e. Nyzul Token farm.
7.) You or a friend has access to floor 96 in Nyzul Isle.
Pseudo-maths:
Kings: 5 Hours ~ 1 day
All that travel and prep-work.
Assaults: 12 1/2 Hours ~ 4 days
50 assaults, averaging probably 15 minutes per assault (some shorter, some longer) means twelve and a half hours.
Einherjar: 53 Hours (9 Real Hours) ~ across the month
Though it only takes 5-10 minutes to complete a run, you'll have to wait on the time gate to finish.
Salvage: 250 Hours (125 Real Hours) ~ across the month
250 Hours?! If you got 120 Alexandrite a run on average, you'd need 250 runs on a 1 hour timer to complete. However, with the price of Alexandrite dropping, you will probably need to resort to buying Alexandrites or farming gil faster than you could get the Alexandrite.
Nyzul Isle: 12 1/2 Hours ~ 4 days
Assuming 6k tokens a run, pretty lowball number, you'd need 25 runs to get 150k tokens. 25 x 30 minutes per run, you'd end up with twelve and a half hours.
ZNM: 8 Hours ~ 3 days
Pictures, Running Around, Killin' Stuff.
Travel Time: 30 Hours
Guesstimate of running to Einherjar, to Salvage, to Assaults, and waiting on people to gather for Nyzul Isle.
Assuming you can play 4 hours a night on weeknights and 12 hours on the weekends with 8 weekend days and 22 weeknights you'd have 184 hours to complete your task.
A way of going about it would probably be..
Day 1
Knock out the Kings the first day or two. Doing Salvage and Einherjar between Kings.
Day 3
Do a Salvage run as soon as you log in, followed by an Einherjar run, then knock out an Assault and repeat.
Day 8
Once you've whittled down the Assaults change to Nyzul Isle during the downtime between your Salvage and Einherjar.
Day 13
Once you've finished Nyzul Isle, you can work on ZNM during your downtimes for Salvage.
Day 17 Onward
Once you've gotten the three items, continue doing Salvage and intermix gil events to optimize Alexandrite purchases.
Enjoy your new Mythic!