Add files to queue: before or after thread.Start()

I have a windows service to process xml files in the queue. The files in the queue were added by FileSystemWatcher event when files created.

The code is:

namespace XMLFTP
{
    public class XML_Processor : ServiceBase
    {
        public string s_folder { get; set; }
        public XML_Processor(string folder)
        {
            s_folder = folder;
        }
        Thread worker;
        FileSystemWatcher watcher;
        DirectoryInfo my_Folder;
        public static AutoResetEvent ResetEvent { get; set; }
        bool running;

        public bool Start()
        {
            my_Folder = new DirectoryInfo(s_folder);
            
            bool success = true;
            running = true;
            worker = new Thread(new ThreadStart(ServiceLoop));
            worker.Start();

            // add files to queue by FileSystemWatcher event
            return (success);
        }

        public bool Stop()
        {
            try
            {
                running = false;
                watcher.EnableRaisingEvents = false;
                worker.Join(ServiceSettings.ThreadJoinTimeOut);
            }
            catch (Exception ex)
            {
                return (false);
            }
            return (true);
        }

        public void ServiceLoop()
        {
            string fileName;
            while (running)
            {
                Thread.Sleep(2000);
                if (ProcessingQueue.Count > 0)
                {
                    // process file and write info to DB.
                }
            }
        }
        void watcher_Created(object sender, FileSystemEventArgs e)
        {   
           case WatcherChangeTypes.Created:// add files to queue
        }

It works perfectly, now I want to add other files to the queue. These files are not triggered by FileSystemWatcher. There is a code to do it.

DetectXML(my_Folder); // add other files to the queue

There files will be also processed by the service ServiceLoop method. My question is where should I place the code DetectXML(my_Folder)?

Before worker.Start() that is

my_Folder = new DirectoryInfo(s_folder);
DetectXML(my_Folder);      
bool success = true;
running = true;
worker = new Thread(new ThreadStart(ServiceLoop));
worker.Start();

Or after worker.Start(), which is likely

my_Folder = new DirectoryInfo(s_folder);
bool success = true;
running = true;
worker = new Thread(new ThreadStart(ServiceLoop));
worker.Start();
DetectXML(my_Folder);