The blank page fear is so real and you are not alone in it at all. I have a shelf of pretty notebooks I bought years ago and could not touch because every page felt too important to mess up. Doing bad quick drawings on purpose is such a smart way around that, and 96 pages of messy hands and coffee cups sounds way more useful than a book full of perfect finished pieces. Making it a daily warmup with a time limit probably helped too, since you stop caring once the clock is running. Flipping through it and seeing it as a diary of learning instead of a highlight reel is a really nice way to put it.

Gotta say, the thumb thing is solid advice but most folks miss the part about letting the handle slide through your fingers a bit on the swing. I had a guy at a workshop show me how to choke up just slightly for balance, and it felt weird for a week but my hits stopped glancing off. Also, don't forget to loosen your grip between swings, death gripping it like a shovel is exactly what tires you out fast. Small fix, but it made me way more accurate on the next hundred nails.