How long does it take, in months, to learn to play harmonica ?

How long does it take, in months, to learn to play harmonica to the point where you could jam with some folks playing blues and not get pillows thrown at your head?

I’m not talking technical brilliance here – just good enough to be having fun on standard blues songs without hitting painful notes or chords every other bar or two..

For the sake of the argument, assume about 30 min. per day of practice, and prior familiarity with music in general.

Thanks!