DAX transform decimal to date

[Anonymous]

All,

Here is my data, below. I'm looking to transform the decimal date ([Vacancy.Year Mo]) to a mm/dd/YYYY format ([Vac.Date]) with as little DAX effort as possible.

And yes, I do need both columns for reasons in the report. Simply converting the column to date format throws an error. wah-wah-waaaah. 

Help me out with the DAX expression to do so?  HUGE thanks in advance! 

Table: 'vac_history'

column:

[Vacancy.Year Mo]
2019.03
2019.09
2019.12
2019.06
2019.03
2019.09
2019.12
2019.06

column: 

[Vac.Date] = ('vac_history'[Vacancy.Year Mo])
2019.03
2019.09
2019.12
2019.06
2019.03
2019.09
2019.12
2019.06

desired [Vac.Date] output after DAX transform:

desired transformation
03/01/19
09/01/19
12/01/19
06/01/19
03/01/19
09/01/19
12/01/19
06/01/19

[wdx223_Daniel]

datevalue(substitute([year.month],".","-")&"-01")