Hey @andigarcia
Thanks for asking a great question that many of our members have had.
You can add past profiles which allows you to retroactively add qualified recipients into a flow that would’ve triggered the flow before it was set to live or manual. This process is formerly known as back-population. Since a list triggered flow allows a profile to move through the flow only once, any profile that has already entered the flow will not be allow to re-enter but any previous profile that has never been through the flow will be added in for the send. The article I linked will provide you instructions on how to do this in your account and links to additional info you migh† need.
Hope this helps!