I think it can happen either way Rue,as LORD dictates.If you read 4 GOSPELS;with regards to the apostles specifically-it seems they were saved and had various degress of "fillings" of HOLY SPIRIT BEfore pentecost! Peter's confession -when JESUS asked "who do men,who do you say I AM"(JOHN?)is a straight forward confession of JESUS.Further,CHRIST sent them out in the POWER of the HOLY SPIRIT BEfore HIS death.
If you read ACTS,starting in chptr 8 thru chptr 19,most of the even numbered chptrs show the various ways LORD annointed believers.ACTS 19 ;to me shows another day of pentecost(Corinth);as well as MANY days of pentecost.Literally,I think LORD continually allows pentecost to empower us to do HIS work.
references ACTS 2:1-5,17-21, ACTS 4:30-33 ACTS 8 :5-17 ACTS 10:43-48, ACTS 11:15-30, ACTS 15:1-15,ACTS 19 :1-10;I think there's one reference btwn ACTS 11-19 where it appears there was a filling of HOLY SPIRIT PRior to salvation;if you don't find it-let me know;will have to look in my other BIBLE.
Lest we forget, HOLY SPIRIT worked thru men of OLD TESTAMENT-specifically the prophets PRIOR to JESUS,remember David's cry to "please do NOT take THY SPIRIT away from me LORD!!!" enjoy,hope it helps