The daily journal page in Zim is a useful place to record one's meeting schedule and task list during the morning planning session, and update these, plus other activities, during the day. I use a custom template for the journal page that has first-level headings of "Calendar", "Tasks", and "Activities". At work, where Outlook is used for calendaring, the "Calendar" section can be initialized by preparing to e-mail a copy of the daily calendar in Outlook, and then copying and pasting the table of schedule data from the e-mail to Zim. However, a graphic representation of the daily calendar is more useful than the textual representation obtained in this way.
The following R script can be used to embed a graphic representation of a daily calendar into a Zim page. The R script plugin must be enabled to use this script.
The first four lines of this script, specifying the meeting names, start and end times, and the figure height should be edited as necessary. If more space for meeting names is needed, the left margin specification of "12" on line 9 should be increased as needed. Depending on your monitor resolution and how much screen space you devote to Zim, you may also want to adjust the "WIDTH" specification on line 5; the value is in pixels.
This script produces a figure like this: