Set Journey tasks in order

Summary:

Hello everyone,

Is it possible to set a chronological order for the execution of tasks in a Journey? If there are for example three tasks, the third can only be executed and completed if I have completed the first and the second. Mind you, I'm not only talking about task completion but also about task fruition: in essence, if the third task involves viewing a pdf file, I can only view and possibly download the file after completing the first two tasks.

Thanks in advance to anyone who answers.

Regards

Elisa