I begin to hollow with a hook tool and a gate.
Now and then I checked for depth. I am sure some people can automatically sight and know how much farther they have to hollow, but I am not one of them. I would rather measure than make a funnel.
Check the outside occasionally, some thing will have to be done sooner of later about the crack. For me, holding it together with CA does not make sense as it always seems to leave an area that is hard to finish without using CA on the whole surface.