[development] allowing some users some days to write stories

I am trying to write a module to allow my web users to write stories just during their birthday web; how can I achieve this? I am using Drupal5 and I suppose it is done using hook_node_grants(), but I don't really get it; any hint is wellcome. thanks -- *La paciència és un arbre d'arrels amargues però fruit dolç. *Hi han dues paraules que t'obriran totes les portes del món: "estira" i "empeny". *Quan fa 6x9? 42!!! (funciona en base 13) *Abans d'imprimir aquest missatge, pensa en el medi ambient.