Thank you for posting! Mine is 8 year old 2e with dysgraphia and slow processing and EF skills. I'm new at this and feel like you. The psychologist pushed accelerate, accelerate, accelerate but how can you skip over so much foundational skills?!
I am using the same math and if it makes you feel better we are only on 1b. We only started last may and it is slow. I have a schedule to catch up and move ahead by going year round. I also feel mastering is important with singapore as it isn't considered a spiral program. We use the intensive practice, speed math, and word problems books too, so it is a lot and we skip bits here and there but not too much and no skip of lessons. I try to have her write at least a sentence a day outside of HWOT cursive workbook, which was a big success. No more printing. I'm an OT and we're done with the start-stop and reversals of manuscript printing. Do start cursive and/or keyboarding early, especially if he is receptive at all to either. Printing is the worst for kids with dysgraphia, and they don't need it if they cursive write. I do teach correct kb, but it is all slow, slow, slow! For me, I feel comfortable to accelerate any content that is conceptual and doesn't skip skills: history and science, reading/read-to literature, writing style/forms and process, and arts. We use a voice notes app on the phone sometimes, so she is more independent and I type it up later. She has to review it all for editing language use and sentence structure and grammar. It is so good to hear from someone who is struggling with the same dichotomy as me. Thanks for sharing. I struggle with it every day.