phd申请收到非正式offer让回复，求指导要怎么回？

收到来自program的director的非正式offer。大致内容如下：You are among the list of the favaorable applicants and we will decide in the next couple of days. At this time, I would like to know, if you were offered a position, how soon we can expect to hear from you about your decision on whether to accept our offer?

楼主目前已经面试了几所，还在等结果。 大概2月中旬才能出结果。
这个算是保底校，请教一下过来人像这类邮件要怎么回比较合适？