At this stage, your child does not have an understanding of size, space and time, so he may get upset when you leave because he doesn't understand what you mean when you say you will be back at 5 o'clock. You may have to do things like bath your child in a bowl without a plughole for a while.
What you need to know:
Your kiddo, at 2 to 3 years, is often fearful. He has very powerful emotions, which he has not yet learned to control. Something new can be very frightening, even if you as a parent, think that there is no risk to your child. He can also be fearful of other people's powerful emotions. Your anger or despair can be very frightening to your child. One of the ways your child may deal with their fears is, he may want to keep the same routine all the time. He may want a drink in the same glass, the same story repeated and the same number of kisses every night. This helps your child to feel safe. It will help if you can look at what is happening in his life and his relationships to find what might be making your child feel fearful, and help your child to talk about it. Let your child know that it is 'ok' to feel cross sometimes. Make sure he knows that you will not let anyone hurt your child.