From Phra Khanong BTS station, take the exit 3. Make a  U-turn when you arrive on Skhumvit road to walk toward Phra Khanong road, then turn left into Soi 69/1, walk up to the T intersection (about 200 meters) and meet at the corner.

Google map link: https://goo.gl/maps/aoZDTXgtPuR2

(there is a 7/11 at the bottom of sky walk condominium just before soi 69/1)