Studio - update fields value using formulas, without affecting existing records

Hi guys, 

Is there a way to change the value of a field in a record, using a formula for instance, without affecting existing records?

For example, in our case, when creating revenue lines records, today users have to fill all fields manually. As some of the fields should take the same value that fields in Opportunities modules, I want to use a formula to define the value of the field (ex: {{}}) etc..

However, if I update the formulas, it is going to affect all existing records, is there a way to apply the formula for records created after a certain date, or other conditions, in the form of:

IF (record created before today), keeps current value

IF (record created today and after), use the formula defined in the field definition.

Overall, is it possible to update any field definition in the studio and then deploy the changes only for certain records?

Any suggestions would be much appreciated.

In advance, thanks a lot for your help.