Hi Adithya,
At the time being, the ACC workflow activity Transfer File (using FTP/SFTP) can manage to stop after having transferred 1 file, through the Planning tab, with the checkbox Execution planned , then select the checkbox Stop planification as soon as 1 file has been transferred.
But you don't have control on what file is taken, based for example on a pattern on file basename, or size or whatever.
Moreover the planification being activated, it is not a precise control on what/when it is done, even if you set it to every hour or every 10 mn.
Alternative is to write specific code with Javascript activity and by using JSPAPI, see method download of ftp class:
http://docs.campaign.adobe.com/doc/AC/en/jsapi/m-FTP-download.html
The idea is to use the method list (belonging also to ftp class) and so get list of files in a folder, then select a file and loop for transfer it, and do what you need in the loop, such as sleep or whatever.
Regards
J-Serge