I wouldn't use 'log in/out', unless it's some kind of online job. For example, I work a second job where teams of people do log into a website in order to score tests, in which case we frequently speak of logging in/out. However, in an office setting where people are physically present, 'log in/out' doesn't work.
I'd say something like "We are going to have an early start on Friday so we can finish early."
Alternately you could say something like "We're starting and stopping early on Friday."
Student or Learner