I had a similar issue I wanted to solve: I have a dashboard showing today’s solar panel output and power usage (time picker set to “Today so far”). I also have solar forecast data (from solcast.com) and I want to display the coming week’s forecast in a panel on the same dashboard.
Setting the Relative time to now/w and the Time shift to 0d/w was as close as I could get for a while. This would display the forecast up to the end of the current week (Sunday). The problem being that the closer it got to Sunday, the less future days were visible.
After some further trial & error, I found that setting the Relative time to +6d and the Time shift to 0d/d does what I want: It displays today’s forecast and the coming 6 days.