Try...Insert Calculated ResultPurposePastes the result of a calculation into the current field in the current record.which the calculation might be..."<" & TimestampFieldJim...
Shouldn't need Insert Calculated Result. The Set FIeld step should work for this purpose in a scripted find.
Script steps that start with "insert" require that the target field be present and accessible on the current layout. Set Field does not.
Here's a script with some scripted find examples that you may find useful: Scripted Find Examples