Here is how I work on thickness to head towards floor tiller and beyond. I use my hand as a gauge with a pencil to mark a line along both edges. I make sure I use the same thickness along both sides of the full bow length.
Here you see 2 pencil lines. I will reduce the thickness to the first line by making a facet with a rasp along both sides of the limbs then remove the center "hump" to a radiused belly and smooth then check floor tiller. If still too stiff I make another line 1/8" to 1/4" below the previous line and do the same as above. These lines should parallel to the back following the backs ups and downs.
here you can see the crown down the center after faceting the belly...
...and after that crown is radiused...
...and then smoothed...
these are the tools I use for this process...