Temporary fillings should be used for as short a period as possible. My dentist tries to use them for 2 weeks or less, and certainly not longer than a month.

I think the best approach is to have the amalgams replaced a quadrant at a time, then wait a month or two after the first ones were drilled out(and after the ones with temporary fillings are replaced with permanent inlays, onlays, or cwowns) before
having the next quadrant drilled out.

When the mercury fillings are placed, and when they are removed is when you get the highest mercury exposure. Also never chew chewing gum when you have mercury fillings(even sugarless gum) as gum chewing releases plenty of mercury from the fillings. I chewed plenty of sugarless gum and ate plenty of canned tuna, so that helped greatly increase my mercury toxicity. At the time I didn't realize what I was doing.

Decreasing the amount of chewing you do will decrease the amount of mercury released. The most important thing is not to have many fillings removed at the same time. Do a few(a quadrant at a time is best), then wait at least a month or two before doing more.