I always Prefill, (luckily all the cars so far have had a more or less vertical (can goes on threads up) filter head).
Doing My first OCI on the Sable, I was amazed at how much the FL400s actually took in. It literally took the majority of a Pint.
(car calls for 5.5 qts, bought an extra qt(already had the 5qt jug), filled a pint Mason jar from it, remainder went in the Filter. and on the next OC, That Filter will be Primed w/the oil from that Mason Jar.)