Quick update from ESA Mission Director Thomas Beck at ATV-CC Toulouse:

Today’s ISS reboost by ATV-4 was successfully completed just before 07:45 CEST. The firing of Albert Einstein‘s Orbital Control System (OCS) engines No. 2 and 4 started at 07:35 CEST, lasted slightly less than 10 minutes and resulted in a ‘delta-v’ (change in Station velocity) of 1.45 m/sec. The manoeuvre consumed 199 kg of propellant.