If you are using SQL Server 2000, you can include in your DTS package the FTP task, do the import procedure, then add a precedence to the next task of your package. This will make the first task of your package to wait until the "new" first task -FTP- will finish. If you have more than one servers you can add more than one FTP task with their precedence contrains that will run SIMULTANEOUSLY.
Another way is to use a new DTS package, do the FTPs there, and then use the execute package task to start the package you already having.
Hope this helps