Don't stress about this, it is never easy to train a child to eat veggies, but its so worth it, and yes starting sooner is definitely BETTER!
No don't feel the need to drown vegetables in ketchup, terrioki sauce or ranch dressing. Yes it tastes better, but these sauces are full of calories and kids need to learn to eat without them, so don't start down that path. Obviously if you're eating a stir fry that contains terrioki sauce like you explained earlier, it doesn't hurt, but just don't feel the need to ADD it.
One thing I did with my daughter was give her one thing to eat at a time, small amounts, and she didn't get the next item until the first was gone. Her problem was that she'd eat all the stuff she like and then start playing with, throwing, smearing, smashing... the rest on her plate. Such a mess!!! So with one at a time she had to eat it, and the things she liked were the reward for finishing her plate. I'm a force feeder (until about 2 1/2), so they know they have to FINISH their plate or Mommy will feed them. But after they're older putting it in the fridge and going hungry is a good option as well. My husband was raised that way and had the same things for about 3-4 meals on occasion. My parents set timers and we had to eat it all before the timer went off, if it did we were spanked and then had to eat it anyway. My 3 year old like the timer idea, sometimes she requests it, make it seem fun for her...
Bottom line. Don't give him stuff to eat like cheese, meats etc, until vegetables and fruit are eaten. The above things are very high in calories and filling, so he won't feel the need to eat if those are eaten first (cheese can stay in the stomach for 10 hours digesting). Avoid snacky foods like crackers, and do things like whole grain pasta, brown rice, ww bread instead. These have lots of vitamins in them that processed foods lack (even the fortified ones).
Best wishes, you're not a MEAN Mommy, but a NICE one, for training your kids to eat healthy, its one of the best gifts a parent can give their child!