Welcome to the flintlock! After a while you may wonder why you ever bothered with anything else. You could also end up wondering why you ever tried one of the infernal things. Several factors go into determining which experience you will have. A properly built, loaded, and maintained flinter will have an ignition time so quick you can't tell it from a percussion. An improperly built, loaded, and maintained one will misfire, hang-fire, and generally drive you to the point where you want to wrap the barrel around a tree. That destructive urge can become almost overpowering if you have just squeezed the trigger on a nice deer and gotten a "clack" instead of a "BOOM!" So lets take a brief look at each of the above factors.
Let's start with "properly built". This is where I add my vote to getting a custom gun. A custom builder has his name and reputation on the line every time he turns out a gun. The frizzen will be hardened properly. The lock will be tuned. The barrel vent (channel from pan to main charge) will be in the correct "sunset position". The pan will mate solidly to the side of the barrel. No gap to allow the priming to dribble down inside the lock. Metal to metal and wood to metal fit will be done right. Yes, there are manufacturers like Pedersoli who do a good job on all of the above but your gun will look exactly like thousands of others and the price of a Pedersoli is often as much or more as a custom would have cost, especially a used custom.
That takes care of the "properly built". It's all about the gun. The last two factors are about you. I think of myself as a "Servant of the Gun". "Properly loaded". With a percussion you pop a couple of caps before loading for the first time that day. Right? Why? To be sure the flash channel is open. Get used to the idea that you will need to make sure the vent channel on your flintlock is open for every shot. I've heard people say different but taking a second to pick the vent will pay off in reliability. So will taking a moment to wipe the underside of the flint and the surface of the frizzen. A friend of mine calls having a black index finger a "flintlock finger". Actually, I cheat and keep a rag tucked in my belt. However you do it, wiping the fouling away will increase reliability. It also gives you a chance to see that your flint is still sharp for every shot. More reliability. When you install a new flint, fire a couple of shots and then check to see that the jaws are still holding the flint tightly. Many years ago I was demonstrating the loading of a flintlock to an attractive young lady at a shooting range. I had changed the flint a few shots before. I confidently brought the rifle to my shoulder, came to full cock, and squeezed the trigger. I saw something fall away from the rifle at almost the same moment that I heard the flat "clack". She said "Your rock fell out." So did my chances of getting a date.
I'm going to hit "properly maintained" very lightly as I'm sure you are already familiar with the subject. There's nothing special about cleaning a flinter that I can think of. In spite of all the wonder cleaners on the market I still use hot soapy water for cleaning followed by dry patches and oil. Never had a rust problem yet and it has been something like fifty years.
Sorry for running on for so long. I wish you success.
John