The bit rate you select depends a lot on the Internet connection speed that you have as well as the typical Internet connection speeds of your viewers.
We recommend you broadcast at no more than 50-70% of the upload speed you have available. Take a speedtest.
We recommend starting on the low end and working your way up. For example if your speed test was 0.70 Mbps (i.e. 700 Kbps) then you may want to start with your total bit rate around 300 Kbps. After your broadcast go to your Diagnostics Report in the Sunday Streams Manager (Reports > More > Diagnostics) and click on the date of your broadcast to see how consistent your Incoming Bit Rate was. If your input bit rate was very consistent then you may consider increasing your total bit rate to 350 Kbps, 400 Kbps, or wherever you would like it.
If your Internet connection is well in excess of 1 Mbps (1000 Kbps) then your concern shifts from your Internet connection speed to the Internet connection speed of your viewers. Unless you are using a multi-bitrate option, then you generally don't want to exceed a bit rate of 800 Kbps so that mobile viewers who are not connected by wifi or those with limited internet connection can still view the stream.