The variable activity works on a combination of SQL and an expression evaluator. We have difficulty determining if a string is validate or not. So in the code we are trying to cast as date and make a determination on this. It is an area we are trying to improve.
For now, try checking out the various Date functions of the expression evaluator. This one will give you the same format.
To_char(Round(Current_Date(), 'MONTH'),'DD/MM/YYYY')
01/07/2017
