Instruction doesn't prepare you at all for playing FO. What it should be preparing you for is anticipation and command of an aircraft. I used to love when a student would get behind a plane on final. Take a look at the terrain and you'll almost be able to predict it. Why does this matter in a jet? You don't want to get slow in a swept-wing aircraft. Being able to predict and be ahead of the plane is critical when you have a crossing restriction to make, and that 150kt tailwind is getting you there awfully fast. It's going to help when the trend line starts dropping down the PFD, you're sinking, and the engines aren't spooling up fast enough for you, which results in too much power and all of a sudden you gain 20kts on short final. If you can see what's going to happen with your student, let them make mistakes and still be able to save the day before things get bad you'll be able to make the transition much more easily.
Instructing makes you a better pilot. Those skills you gain will only help when you get in the real jet where the learning curve is steep and things suddenly are happening about 5 times faster than what you're familiar with.
Go jump in a complex, high performance aircraft with a relatively low time private pilot if you haven't done that yet. It will be just as eye opening. It's amazing how much "faster" things happen when you're trying to think like two people.
I instructed for two years as well. I'm very happy I did and I don't think I would have survived training if I had gone to an airline after only a couple months of instructing. The learning curve is so steep that I don't I could have handled it while trying to learn how to fly an aircraft and learning what my limitations are.