Question about Superchip and a dyno tune.

I have a T/A already with my timing set where I want, and have my 4.10s and a speedcal on the way. My question is when I go to get tuned by Jerry, will he be able to just leave the timing alone and leave it to where I can adjust it myself with the adjuster? or when I get the superchip will I no longer be able to adjust the timing? Granted I won't be adjusting much, but would rather be able to do it myself than have it set with a chip.
 
Don't you need an aftermarket chip when you're being dyno tuned? I'm getting the speedcal and gears before the chip because I don't like to wait. I'd like the chip to just not mess with the timing so I can still play with it with the adjuster. The only real reason I'm getting one is so he can adjust my a/f ratio.