Does the user need to have the Procurement Requester role when a migrated PO is created

Our customer are already live on Fusion with HCM, and the ERP modules are due to go live later this year. When we migrate their legacy PO's into their Production environment, do the Requesters named on the PO line need to have the Procurement Requester role assigned to them before we load the PO data, or can the role assignment happen after the data is loaded?

If we assign the Procurement Requester user role ahead of the go live date, ie when we migrate the PO data, then the users will have access to create Requisitions as their Fusion system is already live. Can the role assignment happen after the PO data is loaded, or does it need to happen before?