[ByTheWay]

Hello everyone,

I'm having difficulty with an example used in Japanese for Busy People II:

今時間がないので来週会ったとき話しましょう。

I'm not sure why た form is used before とき because the event is taking place in the future. So why wasn't the example written like this:

今時間がないので来週会うとき話しましょう。

My only guess is that it has something to do with both actions taking place simultaneously. I'm unsure about this, it feels a bit vague, so I'd appreciate any comments.

Thanks for reading.