Design Pattern Implementation

I am trying to get better at implementing and identifying existing design patterns in code.

Question for software architects or engineers who routinely think in terms of design patterns.

Are you UML diagraming before you implement? it "seems" like this is the way to go, or at least in the beginning. Do eventually evolve the skills necessary to accurately visualize the design pattern(s) and code them in real time?
For more senior engineers, what would your expectation be of another software engineer in terms of proficiency with whipping up design patterns on the fly without first diagraming?