The light begins well before sunrise, so you need to be there early.
About twenty minutes before sunrise, if the clouds are high level cirrus or middle level stratus (and sometimes even low level cumulus), the sky can take on amazing colours.
The intensity peak often lasts only a few minutes. You need to be set up ready to shoot, with the camera on the tripod and set at a low ISO.
I shoot on manual setting, with the focus on “live” view, the camera set on RAW and the shutter operated by a cable release.
The best light of all usually floods the scene in the first five or ten minutes after the sun has risen – giving that special look and hopefully that “wow” factor.