There was a great post on this very topic by @X70037,  https://juniorofficer.army.mil/personal-battle-rhythm/.

Personally I use a mix of three primary things that help keep me on track.

First, outlook. It’s great for those reoccurring meetings, things sent from “higher,” things I can link to my cell calendar, etc.

Next, I have my white board for those “keep them in my face,” things. I also post statuses of projects I’m working on, mostly to keep my supervisor off my 6, but also so I know how much left I need to complete.

Finally, I have my weekly battle rhythm (attached). I can’t tell you how many times this thing has saved my bacon in various staff positions I’ve held. Make it, make sure it has flexibility, follow-it. No matter what job or position you hold, this can be tailored for what you have to do.