For your first time, try 5 mg and see how it makes you feel. I wouldn't recommend any higher because you don't know how you will react to oxycodone. As with any drug, you can always add more later if desired. Welcome to Bluelight!
If you are talking about immediate release oxycodone, not a time release formulation, I recommend 10 and if you feel good at about 30 mins in another 5mg booster dose max, if its oxycontin or time released formulation 20mg for first time user.