Use the IssueTime element tot model this information.
Element

Element	Description
`Invoice/IssueTime`	Specify the time issue in the `hh:mm:ssZ` format. For example`16:50:40`
Example

 <?xml version="1.0" encoding="UTF-8"?>
  <ubl:Invoice xmlns:ubl="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2"
      xmlns:cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2"
      xmlns:cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2"
      xmlns:cec="urn:oasis:names:specification:ubl:schema:xsd:CommonExtensionComponents-2"
      xmlns:vrbl="urn:vertexinc:vrbl:ExtensionComponent:1">
      <!-- Required UBL extensions -->
      <cec:UBLExtensions>
          <cec:UBLExtension>
              <cec:ExtensionContent>
                  <vrbl:InvoiceExtension>
                      <!-- Invoice Transaction Codes -->
                      <vrbl:InvoiceSubtypeCode>0100000</vrbl:InvoiceSubtypeCode>
                      <vrbl:RoutingDetails>
                          <!-- Unique sender ID. Use sender VAT ID -->
                          <vrbl:Sender>399999999900003</vrbl:Sender>
                          <!-- Unique receiver ID. In case of Saudi Arabia always a static value identifies the country and the target version to be created -->
                          <vrbl:Receiver>GENERIC_SA_EINVOIC_1p2p0</vrbl:Receiver>
                      </vrbl:RoutingDetails>
                  </vrbl:InvoiceExtension>
              </cec:ExtensionContent>
          </cec:UBLExtension>
      </cec:UBLExtensions>
      <cbc:CustomizationID>urn:vertexinc:vrbl:billing:1</cbc:CustomizationID>
      <cbc:ProfileID>urn:vertexinc:vrbl:billing:1</cbc:ProfileID>
      <cbc:ID>SME00015</cbc:ID>
      <!-- Invoice UUID -->
      <cbc:UUID>322efd74-5b1b-41e0-843c-1d13bec4475e</cbc:UUID>
      <cbc:IssueDate>2024-09-05</cbc:IssueDate>
      <cbc:IssueTime>16:50:40</cbc:IssueTime>
      <cbc:InvoiceTypeCode>381</cbc:InvoiceTypeCode>
      <cbc:DocumentCurrencyCode>SAR</cbc:DocumentCurrencyCode>