Redirect after APM completes to original uri

Thanks for the interest firstly! I want to change the session.server.landinguri to the uri they originally landed on F5 with. So if a user hits the f5 with /documents/somedoc.pdf I would like to store it and then send them to it after authentication. I thought the landinguri was the var that stored that initial landing not where apm sent them.

So would it be as simple as creating a custom VAR in my policy that stores this initial value and then queue this irule to send them to there instead of the configured landinguri?

so that initial block would read

when ACCESS_SESSION_STARTED {

set landing_uri [ACCESS::session data get "session.user.customvaruri"]

So that would cause the set of the landing_uri later to successfully send them where they needed to go? Also should I use ACCESS_SESSION_COMPLETED instead of STARTED?

Many thanks!