Hi lennycknaus,
As a general rule in arrow building nocks are most often not glued in at all. This is to permit a purchaser to orient the nocks to the desired fletching position. This means that if your particular crossbow requires that your cock vane is face down at the 6:00 o'clock position, then you can easily rotate the nock to achieve this position. If your crossbow requires any other orientation the nock can be rotated to support it.
Since I always orient my nocks with the stiff side of my arrows spine, then I prefer to orient my vanes in accidence with this and I prefer to glue my nocks permanently into these positions. I do not want my nocks ever coming loose or moving. For these applications a Slow Setting Epoxy is recommended. The slower the setting of the Epoxy, the more permanent the bond. I've never had a nock break lose on any of my arrows. Simply glue them and let stand over night. By the next day, they are ready for use.
Regards,
Xbow755