Last fall I was panicking every time I looked up college application timeline senior year because every checklist felt huge. What helped most was making my own mini deadlines that were all 2 weeks earlier than the real ones.
I split everything into 4 buckets: list finalizing in August, personal statement in September, supplement drafts in October, and submission/checking portals in November.
The biggest tip: finish your main essay before trying to do every supplement. I wasted so much time jumping between prompts.
Also make one simple spreadsheet with deadline, portal login, required materials, and whether scores/recs were sent. Nothing fancy, just enough so you do not rely on memory.
Giving myself fake earlier deadlines honestly saved me when school got busy.