It sounds like you're new to opiates and if you don't have a tolerance from using other opiates, 15mg should be enough to start with. Wait and hour AT LEAST and if you're not feeling much try another 10-15mg.
Just go slow. If you're an adult then 30mg-60mg is unlikely to kill you unless you're using other downers, but if it's too much could lead to hours of puking amd regret.
15mg max if you're new to opiates.
If you take other opiates regularly, tell us what and how much/often. There are opiate equivalency charts everywhere online. Some are shit, mind you...
When you say recommended dosing, I assume you're taking them for fun and not a bad back?
Disclaimer: opiates ruin lives, there I had to say it....