因为没有上下文,不能确定这句话语境.
但如果这个等待过程仍在继续,可以用现在完成进行时We have been waiting for him here for a quarter.说明我们还要继续等下去,此动作还未结束.
如果等待已经结束了,可以直接用过去时,We waited for him here for a quarter.
一般情况表示我们已经等待他了一段时间可以更简单的表达：We have been here for him for a quarter.