troubleshooting streaming delay on Google Home device

While testing our Google Assistant action for our audio streams, SC reported that

 I'm still seeing ~100 second delays even on this stream on the Home device. On my phone/browser, it plays instantly.

I tried changing the burst-size but initially did not find any difference - 

64 kB  = 65535   = 100 sec delay - this is the default burst-size for icecast
128 kB = 131072  = 100 sec delay
256 kB = 262144  = 100 sec delay
512 kB = 524288  = 100 sec delay
1 MB   = 1048576 = 100 sec delay

Then it turned out that I was using a relay for testing, and on-demand was set to 1. After setting the relay's on-demand parameter to 0 (so that the relay is always ready and doesn't have to start after a new connection is made),  

128000 = started within 4 seconds!
64000  = 100 sec delay

Repeated this three times, waiting 100 sec + each time after restarting the server. Seems to work well with 128000. So, set this as the burst-size for all our streams.