There is not one resume format that works for everyone. There might not even be only one resume format for you and it could benefit you to have multiple formats of your resume available. For example, if you’re applying for a job and you don’t know whether your resume will be submitted through ATS, submit both a chronological resume and use a functional resume for your in person interview.
When you’re working on your brain dump, make sure to include the name of the company, its location, dates of employment, and several bullet points describing your role and responsibilities for each position you list. Although you may need to expand on the bullet points later on, you’ll need this information at the minimum.