Can I choose when animation in animated dupli-groups starts? I'd like to use some sort of re-usable animations (think little animated effects, simple but a lot of them), that I can play during my main animation, without creating multiple actions, or having multiple nla blocks. I was thinking that animated dupli-groups would be ideal. But can I choose when animation in animated dupli-groups starts? If not, then this way clearly won't work.
Currently this isn't supported

This used to be supported (in 2.49), using the Time Offset field on the empty object instancing the dupli-group.

However support for this is planned. One of the goals for having an improved dependency graph (currently in development), is to have local time for group instances.