Student or Learner
I have checked the calendar that it is Monday on 1st August, and we will visit Japan on that date.
I am going to write this in my diary:
It will be Monday on 1st August by the day we go to Japan.
It is Monday on 1st August by the day we have gone to Japan.
Which sentence is the best or do they need some correction, teachers?
Neither of these is natural.
We will go to Japan on Monday, 1 August.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.