It was the first time that...句式中that

从句的时态问题

在 It was the first time that-结构中，that-从句通常用过去完成时，有时也用一般过去时，有时若有包括现在在内的时间状语，偶尔还可用现在完成时：

I was lucky because that was the second time I (had) visited Japan that year. 我很幸运，那是我那年第二次访问日本。

It was the first time this year that he hadn’t [hasn’t] worked on a Saturday. 这是今年来他第一次在星期六不上班。

上面两个句子中，都用了两种时态，到底有何区别？谢谢!!