Add delay to the ffmpeg output (rtmp->rtmp)

I need to add a delay to the output stream. I tried to do this with tpad, -ss, -itsoffset, but didn't work.

tpad has shown blank frame for random seconds (I don't know why) and then started streaming. (latest part of the stream, and ignore delay).

I want to push a stream to the output rtmp with 10 seconds delay.

ffmpeg -i rtmp://input ... -f flv rtmp://output