To enjoy the most of it you should visit waterfall in a period between the rainy season when there is no rain for consecutive 4 to 5 days.
The reason to avoid during running rain is the waterfalls are located mainly into the valley and the approach road get muddy and is very difficult to find the profile of road and your vehicle may get stuck into those pot holes.
During this period never try to climb the huge stones as they get slippery.
In case of enjoyment remember Not to dive into a shallow waterfall.