Which tense should I use after “by the time you read this”?

Question

Could you please advise which sentence is grammatically correct?

By the time you read this, I have already bought tickets and I have reserved a hotel.

or

By the time you read this, I have already bought tickets and reserved a hotel.

or

By the time you read this, I had already bought tickets and reserved a hotel.

or

By the time you are reading this, I.....

or

Any better way to structure the same sentence?

Answer 1

This is one of the (rather rare) cases when we actually use the future perfect in everyday English.

By the time you read this, I will already have bought tickets and reserved a hotel.

(The "will have" could be repeated, but normally would not be).

In speech, most people would say "I'll" rather than "I will". In a written note, they might use either.