Second way is to make a job which copies data from sys.aud$ table to another table and then delete data from sys.aud$. Schedule this job every 10 minutes. If it will be running every 10 minutes, there won't be much data to delete and NO user will be hanging.
The best way to figure out a find time command is to exec an ls -l so you see what it is finding. Try it on a small group of files where you make the date (I use the touch command). I don't know whether the date commands of find don't work the same everywhere or the docs are confusing, I just figure out what works and use it. I like the unix power tools book, you can find the article about it by googling for "the times that find finds" with the quotes.