Wait for a Flowfile to be picked only after the previous flowfile has been processed completely

I have a flowfile that is a list of files,

that gets split into individual flowfiles (10 in this case)

I am using FetchSFTP to fetch the file from a sftp location, the content of this fetched file is then split and is processed and stored.
In this example: I want to start processing ep.txt only after i have processed bulk.txt after that names.txt and so on.

I was referring to these links:

NiFi workflow monitoring – Wait/Notify pattern with split and merge – Pierre Villard
and 
How to wait for all fragments to be processed, then do something? (ijokarumawak.github.io)

I was able to implement something like this.

but this is not what I was looking for, I want to implement a wait before fetchSFTP 

I tried release signal identifier with filename , but that was stopping any flowfile from moving forward.

Please advise, thank you