Caveats: #1, it does not apply to the OP because he clarified he is asking about FI; caveat #2, for the life of me I can not find the original material.
OK, short of the above, sometime in the past two weeks I’ve read an article, seen an authoritative video, or attended a webinar where the topic was:
Using the throttle’s accelerator pump during engine start
The critical point of the presented material was “hit the starter and THEN quickly jab the throttle to activate the accelerator pump AND QUICKLY pull the throttle back.”
The presented material went on to say, “pumping the throttle without the starter activated means the fuel will quickly pour back out of the carburetor into the airbox. If the engine should backfire, the airbox is a volatile chamber and fire is a real potential.”
UPDATE: the source I was looking for was the EAA webinar “Fly the Easy Way”