i wish to start a tournament. x amount of days per move , but only allowing x amount of vacation time ,can some one from chess . com please advise me .the reason being that  i do not want to make this a no vacation tournament, and to be a little flexible and allow, say 2-3 weeks of vacation time so as not to prolong the tournament.

Unfortunately if you make a tournament where vacation is allowed you can't limit the amount of vacation a player can take. Some members can accrue up to 90 days of vacation.