I'm new at this but I let them sit in boiled linseed oil for 5minutes. I rotate the empty jar of wood biscuits that I have them in to make sure the oil covers it all. Then I let them dry for a week before priming. The link below has quite a good discussion on this.
http://http://www.striped-bass.com/Stripertalk/showthread.php?t=17109&highlight=sealing+linseed+t ime