For major canon updates we would expect that all applicants follow the same one month policy. We do accept some headcanon in filling in backstory of characters where it is not available, however we do ask that players keep in mind what would be contradicted or answered later from future canon updates (as you have stated).

If you feel that there is a significant amount of this character that has not been revealed and would change the way they are played then we would advise holding off on applying until those have been made canon. Small nuances and minor details would be acceptable.