In the year 2070, The Enclave, the shadow government, betrayed the U.S. High ranking officials of the Senate, Cabinet, and military. They were secretly eliminated by Enclave Special Forces and replaced with puppet officials. The Enclave started to take full control over the government. The Enclave, it seemed, was intent on starting a nuclear war, primarily to test the strength of it Vault program. Many started to resist within the Enclave, some were executed, but most, knowing what would become of them, fled to Canada, along with other high-ranking military officials. The dissenters began building support quickly, and formed its own nation, hell-bent on stopping the Enclave plans. With support from other Canadian resistance groups, and the Canada government itself, conducted raids of government bases near the border, and obtained a vast amount intelligence. 2 vital pieces of intel were discovered during their many missions. The first was that the real president, not the president of the Enclave, was being held prisoner. The only problem was finding out where. The second came from a spy within the Enclave, which made the situation very complicated. The situation in Europe and with China were crumbling, and they were getting nervous. The Enclave was planning on using the nukes before the end of 2077.

It is now March of 2076, and time is running out. The Resistance is fighting a war with The Enclave, and its stretching its resources thin. Officials of The Resistance are growing weary of a back and forth stalemate along the border, and believe something drastic must be done in order to save the Earth. Good news is coming however, that may just turn the tide of this struggle.

Well I have one question: When does the RP take place, during or after the events you've vaguely described (which I'd go into more detail with,) or is what?

I'm planning on going into detail of course haha, I just wanted to get down my basic ideas. And I think I want to make the events take place during, like right before the bombs go off.

Sounds like a good place to start. It's where I start all my Prewar RPs. lol Anyway, when making this, also remember to take into consideration the strength of your "Resistance" fighters. Also, you might want to incorporate either in the back of your mind as you write the whole plot and story out, or just putting a little blip of mentioning whether the Resistance is supplied by the Canadian people still living. (Resistance groups usually are supplied by some outside faction/group/etc. but are still somewhat quiet on what their intentions are.)

Besides that, I'd have to see the general detailed plot and more to give better advice.

I edited it, tell me what you think

Looks good not much help I can give on the basis of the plot.