Andrew's only thought as he made his way in the dark to his front door

问题描述:

Andrew's only thought as he made his way in the dark to his front door
接上was how surprised his wife was going to be to see him since he was not supposed to be back until Thursday or Friday.
帮忙准确翻译此句 并指出 as在此怎么解释

翻译:
安德鲁在摸黑找自家大门的时候,只是在想,不知道妻子在看到他后,会多么惊讶,因为自己本不该在周4或周5前提前回家
as这里的意思是:"当**的时候",或者"一边**一边"