Opinion about how long it took for this damage to accumulate

[csaba81]

I'm interested in getting some opinions about how long the damage to the bathroom ceiling in the photo would have taken to accumulate. The source is a small drip in the ceiling that comes and goes. Note the warping in places.

 

In my non-professional opinion it would be difficult to say whether it took months or years but I would venture that it couldn't have happened in days or weeks. Your thoughts?

[Photoguy21]

First question have you stopped the area above the ceiling that has the drip? If not you should. Secondly a few months depending on what a "small drip" actually looks like.