"First Activity" on a Landing Page report

Hi.

I am trying to track the "First Activity" on a particular landing page.

The first activity ideally should be the first time a lead visited a landing page.

But, in a landing page report- a landing page built 5 years ago has a 'first activity' recorded last year. How reliable is this info?

Should it be assumed that there is no activity for about 4 years...!

Is there any way to track the first ever activity on a landing page. Please suggest.