In my experience, they are all different. I'm going to agree with jester though, generally speaking after a couple of tanks the engine is running reliably enough to fly, for sure. How long the engine takes to fully break in is questionable. You will notice smoother transitions and more power the more the engine is run, I would presume once improvements in these areas stop, the engine is then considered broken in.

If you compare an airplane engine which runs for 10-12 minutes maybe 3-4 times a day, as compared to say a weed wacker or chain saw which runs sometimes for hours at a time, it may make sense that the airplane engine will take longer as in more days to break in. Just a thought

On to your venture into flying! Welcome, you are going to love it! Good choice on using a simulator and the apprentice is truly a wonderful flying airplane.