New pencil challenge underway

Ive been working on a new pencil commission for a little while alongside my stag painting and now the painting is complete I can devote my time exclusively to the drawing.The subject is a predominantly white jack Russell terrier,sadly no longer with us.its taken what felt like an age to get an accurate rough drawing together that I was satisfied with enough to transfer by tracing onto my prepared HP arches watercolour paper.In this photo I hope you can see how I'm going about tackling the subject.Having got all the elements in place ears,nose,eyes etc  as well as rough interpretation of fur direction ive defined the outline by adding faint layers of graphite around the dogs fur using a blending stump to apply graphite lifted from a scribbled patch of 2B pencil as well as stealing graphite from the drawn outline itself.there will be a large shadowed area in the foreground and r/h side of the drawing and so I'm going very tentatively with the graphite toning opposite in order that I can balance it all out later once the shadow is in place.Ive made a start on adding darker elements to the drawing(in this case an ear) and having the darker elements in place early on will help me judge the very much more subtle toning required on the dogs coat,both in and out of shadow.the ear as with most of my pencil work is built up with successive layers of graphite starting with an H grade pencil and working through grades HB,B and 2B to build the correct tone,highlights and stray hairs will be taken out using an eraser.Hope you'll all enjoy watching this drawing as it progresses.