It's not known which TCG first implemented this idea or even came up with the name. Regardless, having some form of a prejoin period has become a standard that almost every TCG now follows.
Time PeriodEditHow long the prejoin period lasts varies among TCGs. Some owners sometimes set dates for when prejoin will end, others will cut it off after a certain number of members join. Humorously, some TCGs don't leave the prejoin period and run normally for months without ever having a grand opening.
Cards & DecksEdit
Some TCGs celebrate their prejoin period by offering custom prejoin badges to each of their prejoiners.