Hey @fluid_eye,
You can do something like that, but I would generally prefer to use numbers that are available to calculations rather than text – i.e. %LongDate% – which is not an actual date but a piece of text.
This is probably the least complicated approach I'd take:
WhatsApp Periodic Macro v1.00.kmmacros (10 KB)
Macro Image
Here's another example of a macro that uses date math in a somewhat different context:
How to Run a Macro Weekly and when the Mac is Unlocked - #3 by ccstone
-Chris