How long after taking 10mg of percocet can you take ibuprofen? And how much ibuprofen would be safe?

Percocet and Motrin. It should be safe to mix the two. I would be sure to check with the dr who prescribed the percocet. Percocet is very powerful and for some, can lead to addiction problems. Be careful with the Percocet and try and not take more than is prescribed.
Immediately. The two drugs work by different pathways, and do not interact. Percocet itself is a combination of two drugs -oxycodone, a narcotic, and acetaminophen. There is a limit to how much Percocet you can take due to the acetaminophen. In high doses Acetaminophen can cause liver failure. A reasonable dose of Ibuprofen is 600mg three times a day, although less may be effective.
At the same time. You can take Ibuprofen up to 800 mg three times a day. It is safe to take the medicines at the same time. They are completely different medications.