How long it takes to ripen a hand is highly dependent on summer temperatures. As nights cool down so much even in summer, edible bananas are usually not worth the bother in Sunset zone 15/16/17 climates, while edible fruit might just be possible in hotter summer zone 14 locations, but winter cold damage is also more of an issue. Root rotting in height of summer isn't usually a problem where bananas aren't grown commercially, planting one where it gets the most concentrated heat through the growing season is the best method, with 4 to 6 months of 78f and above and nights above 60ff being better minimum conditions. Only favored spots out in the San Joaquin Valley get those sorts of minimums over a long season, like Modesto or Fresno.