I ask people when they brush their teeth—most people tend to say in the morning—mainly due to the dreaded morning breath we do not wish to cast upon others! However if you routinely brush your teeth only once a day, the best time to do this is actually before bed.
When we sleep our saliva glands turn off, which is our first defence against decay. So if we leave our whole days’ worth of bacteria & food bits in our mouths for eight hours without the protection of saliva, the bugs have an all-night, undisturbed party in there! And this is where problems start.
Technically, plaque does not become damaging for 24hrs so it is okay to only brush once a day—but it must be done before bed! (Though I’m sure your work colleagues & loved ones would prefer you without the morning breath as well!)
Go easy with the scrubbing