Whatsapp message at any given time?

My boyfriend has a birthday soon and I would like to send him a whatsapp message at 0:00 AM. But since I'm going to be at 0:00 AM, this has to be done by a program.

How do you do that?

I'm also equipped with laptop, RaspberryPi and such things.

If your best friend means something to you, stay awake until 0:00. Otherwise, do it right after getting up, it will be just as happy.

That with the program should be the surprise

Make an alarm clock at 23.59

Nah, 23.50 is safer ;-)

I do not think your best friend will be happy if you wake him in the middle of the week at midnight.