I hate to rain on everyone's parade, but "plateaus" are nothing more than indicators that you're doing it wrong and need a change. A true 'plateau' should be considered a period of 2 or more weeks of no progress with the same previously-successful conditions being applied.
Everyone that says they plateaued for X months is lying to themselves. You didn't plateau, you were doing it wrong. It's not like your body is going to suddenly go against all the laws of physics in order to hold onto its current weight.
If you reach the two week mark and things aren't changing, then you definitely need to reconsider where you're going wrong. Exercises not frequent or intense enough? Need to alter macro-nutrient ratio? Increase/reduce calories? Switch the type of exercise you do? Decrease sodium intake? It's different person to person, but one thing is constant: you need to do something
ellyfranklin's post is the perfect example of this. She saw that there was no change for two weeks, increased her workout intensity, altered water consumption, and her 'plateau' never had a chance.
So to answer to original question directly: If you're doing everything correctly, you shouldn't have a plateau, ever. If the conditions are no longer prompting weight loss, give it a maximum of two weeks before you start applying changes.
If you think my post is too abrasive, harsh, or offensive, you're:
B) Too sensitive.
C) Not going to receive an apology for pointing it out.