Wargaming has a new developer post on the World of WarPlanes site that lays the groundwork for the forthcoming open beta. The date has yet to be determined, but Wargaming has revealed there will be a "hard server" wipe to reset everything in the game prior to the start of open beta.
Open Beta: Stage One
The first stage of Open Beta will see the implementation of this Token system. The only exception will be Premium account status; that will be given automatically to all players.
Open Beta: Stage Two
The second stage of the Open Beta test will will have another wipe of the remaining Premium accounts and Tokens. At this point, all existing Tokens will be converted into Credits. From this point on, all Tokens earned are redemable for Premium account time.
Read the entire post on the World of WarPlanes site.