Automating Date-Based Updates?

I am a new Access user. I have created a database to track and inventory animals brought to a local animal shelter. The database includes information such as when the animal was brought in, who dropped it off, when it was adopted (Hopefully!), etc. The database is being used by people who have limited computer experience and the challenge has been to automate it and simplify it as much as possible. I have created several Switchboard pages to try and accomplish this.

I have done research through Google and MS support and have found little help with a solution to this problem:

When an animal comes to the shelter, it is held for three days before it becomes available for adoption. I have created seperate fields for Date In Day, Date In Month and Date In Year. There is also a field detailing the animals adoptability status. This field is left blank in the intake process, and is then manually updated to Adoptable, Biter, etc., after the three day period. Is there a way to automate the Adoptability Assessment Field (which is a Lookup Table Field) so that it changes from blank to Adoptable after the three day period? (We have very few animals come in that are marked as Biters, so I just need the field to change over to Adoptable after three days have passed. Unless a solution can be presented to filter animals with Biter status out of the solution.)

I truly appreciate any help that can be offered.