On Saturday, in the office, especially in the evenings, we feel like skipping of the work and jump out to home soon. But remember your dedication towards the work would be observed by the office management in such kind of situations.
So remember that you do not skip or postpone any work on the weekends. Instead you can control the number of working hours in the office by reducing the time for other issues which are not related to main office work.
Reduce the lunch time. Eat quickly and go back to work soon.
Stop interacting to colleagues if the matter is not related to work.
Keep a filled water bottle on your table, so that you need not waste time to walk for it always.
There can be some more situations where you can save time. Depending on your office conditions, analyze them properly and plan accordingly.