I would be careful about what you believe when you hear people attacking a chelator like DMPS. There are groups which love their particular method and will bad mouth the others. Cilantro is attacked a lot too. There are people who have used them both successfully. The key is to find a method which works for you. It's important to use a method which other people have used successfully. Chelating is not 100% risk-free, so complete improvisation is not a good idea.
Keep in mind that chelating is going to affect your liver no matter which chelator you choose. There are ways to lessen the effects, but your liver is going to have to work to get the metals out. There's really no way around it.
To make it easier on your liver, you can start with smaller doses of your chosen chelator. Try not to overdo it in the beginning.
I use cilantro and chlorella roughly every 4 hours, including waking up in the middle of the night to take it again.
The recommended schedule for ALA is 3 hours. You can stretch that to 4 hours at night. Some people say that 2 hours or 1 hour is better. I would start with 3 and see how you feel. You should wait until 3 months after you have replaced your fillings before beginning with ALA. I'm not sure if that's an issue for you now or not.
The recommended schedule for DMSA is 4 hours (plus waking up at night).