This will give you say a perfect 3 8 caulk line with an irregular wall to counter gap.
Big gap between counter and wall.
If you can t do that then you are in over your head with this house and it will do noting but bleed you dry paying for people to do work for you.
An obvious gap between a countertop and backsplash is unattractive and it can allow water to seep through.
Remove the excess countertop up to the pencil line with a belt sander and a coarse 60 grit sanding belt.
Set your compass to fit the tip in the widest gap between the countertop and the wall.
If the countertop isn t level slide shims between the countertop and the support struts of the cabinet frame to level the countertop.
You ll need a drill with a no.
It s supposed to be behind the counters and cabinets.
The line will continue maintaining caulk gap regardless of the gap of the wall to counter.
Close the gap between counter and wall if the gap between the countertop and backsplash is more than 3 8 inch it s generally too wide to fill and is best handled with trim but you can try to close the gap to give yourself the caulk option.
Your tile person will take the largest gap and run a tape line using that as the thickness or the caulk.
If the gap is too wide to seal with silicone narrow trim molding can solve the problem.
Tiles are started 1 8 off the counter leaving gap for caulk.
If the gap cover is shorter than the depth of your stove leave a gap between the wall and the cover.
Measure the depth of your counter and cut the cover if necessary.
If it s not too wide i d line the back of the counter with crown molding or wall trim of some kind paint it with a high gloss paint so that it s washable.
The fix is to remove those counters and actually fix the wall.
Measure from the edge of the counter to the back of the stove to determine the correct size for the gap cover.