First Grid Sketch For Large Painting

I have been wanting to paint sealions for a very long time  The CAM Biennual is coming up which motivated me although I don't think I'll get it done before then.

I found this photograph that I took of them and decided to paint it since it would fit the long canvas I want to paint it on.  I sat down late last night and tried my first grid sketch study.  After the second or third box, I was mostly following the photo but I kept feeling myself start to go bigger and then the grid lines would stop me and pull me back.  It was very interesting.   I have always struggled with layered and multiple objects and the grid sketching definitely helped break down the objects into shapes and value so my brain couldn't only see a pile of sleeping sealions.

I have my huge canvas mounted on the easel and a cup of coffee in hand and am fighting the fear of starting such a large canvas.  I am trying to just think about my steps to take just like the smalls.  Just do the underpainting and then sketch it out with burnt sienna and then go for it... (oh, and remember to just have fun!)