Paragraph styles

Hi- I'm returning to page design after long career as an Visual Journalist.

Question: When laying out any brochure and after placing text do you go through this text assigning fonts font styles font sizes indentations ect., return, reselect the fonts and assign it a paragraph style? Or do you create your paragraph styles first?

Seems like it would be difficult to create paragraph styles when you're still in the early design stages of your layouts.

Thanks!