The old joke goes that little Johnny's parents got him bass lessons. The first week he learned the notes on the E string. Second week we learned the notes on the A string. Third week he skipped his lesson, and his upset parents confronted him in his room. "Johnny, why didn't you go to your bass lesson? And what are all these beer cans and cigarette butts doing lying around here?" "Hey, don't cramp my vibes, man," Johnny replied, "I gotta get to a gig!"
To answer the question - depends on what you mean by "play." I started playing bass about six years ago, nearly seven now. I bought the instrument and a little practice amp in September. I changed my routine to get up at 5 every morning and practice at least half an hour (with headphones). About Christmas I was getting bored of playing along to CDs and started looking at Craigslist for jam partners, and found a group about February or so. Were we good? Ummm... no. I have a youtube video from an open mic we played that's pretty embarrassing. But we could stumble through songs together, and it was a start. Broke up after a year because some of us wanted to gig and others weren't getting there. It was after two years of playing that I fell into my first real gigging band and a couple of years after THAT when I got into a classic rock power trio that was genuinely GOOD and could keep up.
I was able to self-teach pretty effectively, but for most people it's good advice to get a teacher. Practice every day, you'll learn more in twenty minutes a day than cramming five hours into a single marathon session each week. Learn about music theory - scales, chords, etc. Some people insist on One-Finger-Per-Fret but it's really not necessary, especially low on the neck; "Simandl" 1-2-4 fingering works just fine (that basically means use your four fingers to cover three frets, not four, and shift your hand position as needed).
Split your time between learning theory and technique, which make you a better musician, and actually learning songs, which are why you want to play bass in the first place. Learning to read music is a big plus - Ed Friedland's books from Hal Leonard are good for starting you off in that direction. Train your ear - try figuring out parts just by listening and playing along on your bass (hint; knowing music theory will CONSIDERABLY speed up your ability to figure out where a part is going). You can find "tabs" of songs online to learn songs from. Nothing wrong with that, but don't rely on them too much; they're often wrong and are no substitute for a good ear. I used them a lot early on, then weaned myself off them, but I'll still look one up from time to time to help figure out a tricky part, especially if I'm in a hurry.
And take care of your hands! Learn to play with a firm but relaxed hand. Overtension and unnatural positions can lead to carpal tunnel and tendinitis, which suck and can end your playing permanently. I'm not a big fan of youtube teachers, but this one is relevant - https://www.youtube.com/watch?v=VRkSsapYYsA .