About: http://webisa.webdatacommons.org/423997588

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	2 - Yes, it updates, so i personally think that the best practice is to start channel it at 21%, generally the first tick will hit right when the boss is on 20% mark cause the raid damage drops him fast.
http://www.w3.org/ns/prov#wasQuotedFrom	mmo-champion.com