We reached Colombo Airport on 22nd September in the morning. After clearance from the airport, we headed straight to Colombo Fort railway station. The airport is situated on the outskirts of Colombo, and thus a bus/ taxi would take you to the main city. We opted for AC bus, which cost us much less than a cab, and reached central Colombo. From there, we walked to the railway station and got the tickets for Rumbukkana Train Station, that is close to Pinnawala.
It was a local train- no AC and open windows, but the weather was good and thus made the ride quite pleasant.
Upon reaching Rambukkana railway station, we took a tuk tuk to our B&B in Pinnawala. It is a small area, and does not have much to offer. The only attraction is the elephant orphanage and a zoo, and both can be covered in less than a day. 
Bathing Elephants

Marching towards Orphanage

Baby Elephants in Orphanage

Pinnawala Zoo

We visited both the places on the same day, had dinner and headed straight to the guest house after the sunset, to hit the bed.
Most of the places we visited (apart from Ella), life comes to an end after the sunset. The shops, all the attractions and even the restaurants would close. There are very few street lamps in the country, most of the streets are dark and there are LOTS OF street dogs, so it is highly recommended that your wind up your business, and reach your hotel as soon as possible- there’s no point in staying out late anyway.

Next morning, we woke up by 7:00 AM, really fresh after a proper full night sleep. We checked out, and took a bus to Dambulla.