transition between idle and streaming.

I want to make a streaming avatar. The original guidelines by D-ID say that we should put in an idle prerecorded animation and play it when not streaming. I have two questions:

Can we do continuous streaming (no idle prerecorded video in place). I know this may be costly, but we are fine with that.
If we use idle prerecorded animation, is there a way to make the transition between idle and streaming look more natural? currently, the transition is very abrupt and unnatural.