Hi Manju,
Though Jog Falls is open at all times, it is advisable to go there in the morning for better visibility.
It will take you around 4 hours via SH 93 and NH52 to reach the falls. Hubbali airport is 175 km away from the falls if you use this route. Another way is via the Kumta - Hubli road which will take around 4 hrs 18 mins.
I hope you find this helpful.