First off, welcome to Bluelight! Hope to see you around after this question is answered, we've got forums covering..well..pretty much everything.
If you have zero experience with oxycodone, the best starting dose is in the 5-10mg range. I'm assuming that 120-130 is in pounds, not kilograms? Correct me if I'm wrong.
Go ahead and start with 5-10mg, wait 45 minutes to an hour and see how you feel. If you want to take more, you can, but I wouldn't go any higher than 20mg for your first time.
Lucky for you, oral is quite an efficient route of ingesting oxycodone.
You may notice itching with oxycodone, this can be solved by consuming an antihistamine such as diphenhydramine (also known as Benadryl) 30-45 minutes before consuming the oxycodone. Bear in mind that diphenhydramine and other
first generation antihistamines generally have sedative effects, which will enhance the sedative effects of the oxycodone. Usually this is desired by the user anyway, so its a one-two-punch of knocking down the itching and improving the opiate high at the same time.