In general, for each service expect ONE or TWO service disruptions, each one estimated to take around 3-5 minutes in 2 separate mornings during the following maintenance windows:
Monday, 22th of April between 5:30 and 6:30 local time (3:30 - 4:30 UTC)
Tuesday, 23th of April between 4:00 and 7:00 local time (2:00 - 5:00 UTC)
Best regards.
Monday, April 15, 2013