If your clients are RTMP and/or RTSP you would just need to set your stream type to "rtp-live". When using the "rtp-live" stream type in your application's configuration file, the source stream will be published to Wowza only when the first client connects to the stream
For HTTP streams to be active, the data packets need to be packetized. Wowza will start packetizing the HTTP stream as soon as the stream is published. The stream is not published if there isn't at least one client requesting the stream. So basically, an HTTP client can not be the first to request the rtp-live stream. Once the stream has been published by an RTMP client, HTTP clients can connect.