Many times in such scenarios the trigger is when the flat file appears in the input folder. The file adapter polls the folder every few seconds and when it discovers a message, it delivers it to any orchestrations or send ports that are listenening. If you want the trigger to be more of a scheduled event, then you could configure the receive port to use a service window. For example, if you want you receive the flat file at 1:00, but you want your process to run at 2:00, you could configure your receive port with a service window of 2:00 – 3:00.