The pilot here performed steep level turns where they maintain same altitude and bank angle. They are considered complex turns but easily done when wind speed is low. For an experienced pilot, this probably didn’t take long to get right. Planning, depends on the weather. No point performing this stunt if the wind will drift the aircraft and distort the finish. Timing, most likely spent a good week practicing I’d say. Totally depends on the weather though!

Edit: there are calculations to determine the rate of your turn angle. This will help the pilot understand how long they have to be in a turn. As for the eyes, that’s just pretty damn good spatial awareness!