Official comment
We do have a planned feature that I think will get you where you want to be; an evergreen timer function on Pages where you can set it to the number of hours / days you want to countdown, and the timer starts when the contact first visits the page. The advantage of this planned feature is that there is nothing to do to make it work other than setting the timer and redirect on the Page. Ontraport takes care of keeping track of the time and redirecting the page for that contact when time is up.