While it's perfectly clear to me that one can use the present tense to talk about scheduled and fixed events in the future:
Our train leaves tomorrow at 9pm.
and so on, I've seen and used this structure myself many times while talking about plans for the future. My question is: is it grammaticaly correct? And if so, why is it never covered in any textbooks?
Tomorrow, you have to tell him why I haven't handed in my essay yet.
I have a date next week.
and a little more complex one
Here's the plan: I'll find a parking spot, while you go look for a place where we can eat. Then you call me and tell me where you are so I can join you"
In the last example, would there be any difference if instead I'd go with "Then you call me and I'll join you" or stick to the present tense in the first part, as in: "I find a parking spot..."?