While Kyoka's answer is 100% true, we can at least find averages.
If you're breeding for a Pokémon with 20 egg cycles (roughly the average for Pokémon that can breed), then it'll take you about 2570 steps to hatch it if you have a Pokémon with Flame Body or Magma Armor in your party. You can have up to 5 eggs in your party at once, but sometimes you get a bit unlucky with when the day care finds the egg, so you might not always have 5 eggs. Let's assume that you can hatch 3.7 eggs per 2570 steps on average.
My own testing showed that it takes about ~1.77 seconds to move 10 steps when using the Mach Bike in ORAS. The egg hatching animation takes about 20 seconds per egg, and depositing a breedject in your PC takes about 10 seconds. Let's also assume that you're not 100% efficient and add a 1.3x multiplier to the end result for miscellaneous lost time.
Full odds:
(4096 * (2570/3.7) * 0.177 + 4096 * (20+10)) * 1.3 = 814,392 seconds, or 9 days, 10 hours, and 13 minutes of nonstop hunting.
Charm odds:
(1365 * (2570/3.7) * 0.177 + 1365 * (20+10)) * 1.3 = 271,398 seconds, or 3 days, 3 hours, and 23 minutes of nonstop hunting.
If you want to compare against Masuda odds:
Masuda Method, no Shiny Charm:
(683 * (2570/3.7) * 0.177 + 683 * (20+10)) * 1.3 = 135,798 seconds, or 1 day, 13 hours, and 43 minutes of nonstop hunting.
Masuda Method + Shiny Charm:
(512 * (2570/3.7) * 0.177 + 512 * (20+10)) * 1.3 = 101,799 seconds, or 1 day, 4 hours, and 17 minutes of nonstop hunting.
Keep in mind that these are all averages, with quite a few assumptions and estimations thrown in. How long it actually takes you will likely vary drastically from these numbers, either longer or shorter.
