I am developing web video call with Amazon Kinesis WebRTC using by javascript.

Flow is first I create signaling channel when master wants to start video call So If viewer wants to enter the video call before master. I need to check if signaling channel exits.If not I want to show a warning like "Host has not started video call please wait". Then I want to remove this warning when master create signaling channel. Is there any way to do it? Thanks in advance for any help.

Ps: Master and viewer already define signaling channel name before master create it.