When is it appropriate for a country's citizens to rebel against it's own government?

Depends what you mean by "rebel".
Is it violence with fighting in the streets, or is it an ongoing peaceful protest over an established law?

A people should not respond to their government with violence unless violence has been perpetrated against the people by the government in question.

A peaceful protest is always appropriate, especially in a country where people have the right to voice their opinions and wants publicly.

And yes, protesting against a government without violence is a form of defiance and is by extension a form of rebelling.

When they try to fundamentally change your country to socialism. You weaponize the FBI and give billions in cash to countries hell bent on killing us.

If you really able to rebel against your own government for certain issues that means you have a good governance there

if rebellion happens, it means that the government has started oppressing and is conducting itself against the wishes of the people. If a rebellion means that people have not been given a medium to voice out their concerns.

Like when the tyre of truck runs over our leg .. we shout to alert the truck driver who is expected to stop and do the needful ... but if the victims mouth is shut or never heard, then it is tyranny which is progress without concern.

When they try and take our guns!

No dissolution of government should be lightly taken by its citizens but when a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new Guards for their future security.”

I think the real question is when isn't it