how to get metadata before executing a block of code

I have some code that I am using to create a Document Set when a document is uploaded into a library. The document set is created within the library...I am currently doing this in an event receiver (ItemAdded). The problem i am having is...when the document is uploaded, I want the user to be prompted for some metadata, which will help determine which block of code to be executed and i can't seem to get this done. Is there a way to get the logic to get the metadata before executing the rest of the code?

public override void ItemAdded(SPItemEventProperties properties)
        {
            try
            {
                SPSecurity.RunWithElevatedPrivileges(delegate()
                {
                    SPWeb currentWeb = properties.Web;  SPListItem listItem = properties.ListItem;
						SPList myList = listItem.ParentList;
						SPFolder mylibrary = myList.RootFolder; 
						SPList FirstList = currentWeb.Lists["First List"];
						SPList SecondList = currentWeb.Lists["Second List"];
						var IsAFolder = IsFolder(listItem);
                            //1. Check to see if object added is a document
                            if (IsAFolder == false)
                            {
                                this.EventFiringEnabled = false;

                                string EmployeeName = listItem["Employee Name"].ToString();
                                string EmployeeID = listItem["Employee ID"].ToString();
                                string DocumentSetName = EmployeeID;
                                string DocumentType = listItem["Document Type"].ToString();
                                SPFile fileSource = listItem.File;
                                string EmailAddress = FirstList.Fields["Email List"].ToString();
                                string FromEmail = SecondList.Fields["From"].ToString();
                                string EmailSubject = SecondList.Fields["Subject"].ToString();
                                string EmailBody = SecondList.Fields["Body"].ToString();
                                //2. Evaluate the Document Type
                                if (DocumentType == "Assessment")
                                {
									//execute some block of code
                                }
                                else if (DocumentType == "Certification")
                                {
                                    //execute some other block of code
                                }
                                else
                                {
                                    //bla bla bla.
                                }                

                            


                        }
                    }
                });
            }
            catch (Exception ex)
            {
                SPDiagnosticsService.Local.WriteTrace(0, new SPDiagnosticsCategory("My Category", TraceSeverity.Unexpected, EventSeverity.Error), TraceSeverity.Unexpected, ex.Message, ex.StackTrace);
            }
            finally
            {

            }
        }

Part of the metadata that is entered by the user is the "Document Type", and I want specific blocks to be executed depending on what the document type entered is. Right now, i can get this to work the way it is designed cause the metadata input screen is popping up at the very end. What am I missing? 

Thanks for the help