At this stage, for your child, concepts are something he is still unaware of – the concept of time, date, day, position, etc. It is the time when you can start building upon concepts and hone his cognitive skills.
What you can do
Talk your child about concepts. Pick up stories that have a lot of daily concepts. Talk in a way that will make your child understand what different concepts are all about. A child has very little knowledge about concepts. He will take time to understand and comprehend what is being talked about. (For eg. We are going to the park tomorrow. OR Yesterday night, uncle Jem came to our place.) Sentences like this will help your child relate the time and date that is been talked about.
Keep it simple in the beginning and allow your child to think and relate. Don't give the answer readily, rather allow your child to comprehend and co-relate the incidents that are being talked about. This way, with a little help he will understand simple concepts like today, yesterday and tomorrow along with sense of a day. Kids have very quick thinking minds. A little help and a kid can ensure that he picks up the right points and understand what is being told. So, a little help will give your child a fair knowledge about the concepts that he can hone in his growing years.