I drilled 2 holes as you can see in the picture. And not sure how to do the offset based on that mounting position is there a guide20200322_145928 on how to calculate out the offset?

I did look in to it but not sure exactly on what to do. Not that advanced in 3D printing.

Never Mind I see where you did the math.

No need to “calculate”. Just measure the offset between the tip of the BLTouch and the nozzle. You can do that with a sheet of paper.