Using Modifiers BY with MINOF

Dears,

I am trying to get the first Month we have data of a customer to group it by cohort, and I want to add that date as a property of customer.

I was able to get that data using the following formula:

'Requests MRR BE'.Date[BY FIRST: 'Requests MRR BE'.'Company or Partner Id' ]

The problem is that it only works as long as I have sort the date ascending in the transaction list, and I would like to retrieve that data without having to sort my transaction list. Is there a way I can integrate MINOF in a modifier so that instead of the first value it finds it takes the smallest?

Thank you very much in advance,

Jose