It seems surprising that the present tense can be used for future actions. But it is true but only in certain situations. Let us see one of those situations.

The Present Simple for an action scheduled in advance.

Normally we use the Present Simple Tense for the repeated action. Besides this, it can also be used for the future action which is decided beforehand. Let’s take an example.

The train leaves at 7am tomorrow.
Here the time table of the train is being discussed. The time table is already decided in advance. Therefore the future departure of the train can be stated with the help of Present Tense.

The prize distribution function begins at 6 ‘o’ clock in the evening on forthcoming Sunday.
I have got the tour details. We spend two days in Delhi.
We have booked the hall for tomorrow. We start our celebration as soon as all the guests come there.