Hello WDC Members I hope you can help me...

I am having some problems metering to use my ND Graduated Filters.
This is what have been doing so far...

Set up my tripod and find a good shot.
Place camera into Liveview, Manual Mode and Spot metering.
Point camera at foreground, Set Aperture to F11 and alter shutter speed until meter reads 0
Point camera at sky and see the meter go way off the scale (past +2)

At this point is there anything I've done wrong?
How do i count how many stops it needs to come back to 0 when its off the scale?

Are there any other points/tips people could give me :-)