Internet Radio peak listening times are a bit different than from traditional AM of FM radio. Since most people listen to the radio on their way to work and on the way home, morning (6:00 - 10:00am) and afternoon "drive times" (3pm - 6pm) usually are the peak listening times for AM/FM radio.
For internet radio, it seems that most people listen during the day when at work. So for instance, if your station is in the US) the peak listening time is between 9:00 am to 12:00pm then again from 1:00pm till 6:00PM. Early morning and evening listening is usually a bit lighter. Weekend listening varies a little with Saturday being the heavier listening day. We must also consider the various time zones throughout the world.
As internet radio accessibility gets much easier, these times will change. We may see much more listening in the early morning ours. We are beginning to see this trend with the access to many apps such as Tunein etc. Google and Amazon devices are another source for much easier internet radio access.