My suggestion would be to use the PFC File Service object n_cst_filesrvwin32. It has two functions, of_GetCreationDate and of_GetCreationDatetime, that will return the creation date of a file.
If you do not want to use the PFC service, look at the PFC object pfc_n_cst_filesrvwin32 in pfcapsrv.pbl and examine the script for the of_GetCreationDatetime function. It will point you to the external API function calls and structures you will need to create a similar function in your application.