To be honest, I am not sure Excel is really the best tool for this type of thing, and the setup will make things challenging (try to avoid merged cells for example)... but, regardless, attached shows you how you *could* do it -- I have only populated Jan & Feb, and the practicalities of this approach will diminish the more data you end up with (obviously).
The attached basically has the following calc replicated in each cell below the individual dates:
Note, when updating remaining months, the above formulae can be copied and pasted (as formula) over remaining months / cells, no changes are required (simply copy & paste job).
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