I say, and with God's success: It is not permissible to have intercourse before performing ghusl if she has purified for less than ten days, except if the time for prayer has passed such that she has not prayed and the prayer is due upon her, then intercourse is permissible even if she has not performed ghusl. If she has purified for ten days, then intercourse is permissible even if she has not performed ghusl. And God knows best.