For Charming purposes....it depends. There's no hard and fast rule for it, but make sure you know the context of the engagement/betrothal. It'll generally depend on the relationship between the two parties; long standing public betrothals would require a bit longer mourning periods than say shorter engagements. Google also says "In the event of the death of a woman's betrothed shortly before the date of the wedding, she may wear black for a short period or full mourning for a year." (ty for that Beans) which seems reasonable as well; going right back out into society after a death so close to the wedding would definitely raise eyebrows.

So if you were to look at it on a X + Y graph, the closer the two parties were to each other or the wedding, the amount of time would go up. The more distant from the wedding and less close the two parties were, then you'd see the amount of mourning time dip. But it really is contextual.

I realize this explanation might leave you with more questions than answers I AM SORRY, MY ADHD MEDS HAVE WORN OFF TODAY

DM me if you have questions but yes essentially it depends. Using the pre-existing mourning doc that we have, you can look up the closest relevant situation and then adjust from there given the above xD

EXAMPLE
Athena's character Elise's betrothal was made in the summer of 1893. No exact wedding date was planned yet and she has only ever met the man a few times, but he is her eldest brother's close friend.

So close families, but short betrothal period. From our Mourning chart, a woman mourning a husband would be 6 mo full mourning, 1 year partial. So using that as the blueprint, the amount settled on was 2 months full mourning, 3 months partial.