Djokovic should understand the logic of the time rule. Just because you're standing on the line doesn't mean you aren't delaying the game. Otherwise you could rush to the base line and bounce the ball 56 times and not get a time delay.
Djoko is starting the event the hard way: Fognini and Dimitrov (ranked 36 and 31). Compare that with Murray: Donskoy and Lu (ranked 83, 79), Rafa: Harrison and Mayer (73, 64), Fed: Istomin, Dodig (43, 60).
Djoko cannot settle in the event, he has to be sharp right away.