"Syncing" the animations at the viewer side is not a solution... It may "look right" for you once "synced" this way, but won't for others.
Sadly, there is currently no good solution in SL for syncing animations (like there is, in LSL for pre-loading sounds and thus allowing to sync them when played)
before they get played once (i.e. they got downloaded and cached) by everyone's viewer...
This would be a good question to pose at the
Simulator User Group meeting (there are also already several JIRA issues about this, e.g.
BUG-3455).