January 1st 1821 - The End Of A Journey
A 4 centuries long one at that!
Well, I started by taking a look at the general situation. Quick glance at the different map modes, check the ledger, the national ideas, sliders etc... And well, the verdict? We are incredibly strong, and could possibly take on pretty much anyone.

Hedjaz at the end of the game
First enemy was Vijayanagar, as we had 3 large armies massed on their borders, they were defeated pretty easily and soon enough we controlled a large enough portion of their lands to claim the whole western Indian coast.
What I didn't notice was that this put us above the infamy limit, but when I did notice that all I thought was "Whatever". It was too late for that to harm us anyway. I wanted to do some conquering and certainly had the means to do it!
Now, a list of all the other (not so) important things I've done, kind-of in chronological order:
-Build lots of universities and fine art academies, I know it's too late for them to be worth it but I had money lying around being useless so...
-Increase army size. While we had a very large army, many parts of our realm were undefended and our armies had to constantly march from end to end. Rather than split them up I just built new armies to cover areas where there was no one. I think I conscripted a total of around 60-70,000 troops.
-Invest all into Stability(no tech gives any real bonus anymore anyway) and change the last National Idea from Divine Supremacy to Revolution and Counter-Revolution for the free casus-belli, especially against UPCA, but also because it's the coolest NI out there.
-Take the last step towards full centralization.
-(Try to)Convert the heretics of the north to the one and only True Faith.
-Fight lots of defensive wars("Dishonorable scum") during which we made some important gains. (Kazan and Nizhny Novgorod as vassals, 1 or 2 provinces in Russia, full annexation of Baluchistan and some OPM north of them. Plus lots of little money and prestige gains from lesser opponents)
-Fail to fulfill last ruler's dying wish. I did try, by getting our fleet all the way around Afrika to Egypt, then sending 30 regiments to UPCA which we declared war on by using "Revolutionary War" Casus Belli, however they had lots of European allies that joined in and my assaults against their forts failed so... Sorry.
-Declare war on the Ottomans and kick them out of Anatolia + make them revoke a few cores for added humiliation. I hate those guys, always good to see them suffer.
-Think of breaking the truce with Bavaria to take revenge on our last defeat against them, but decide against it...
-Face and fail to counter revolts in some parts of the colonial empire.
...And that was pretty much it. Was really fun while it lasted, that's truly one huge empire we built together, over the months. We should
totally do this again some other time.