According to EMH, when is a dividend (to be paid soon) first reflected in the stock’s price?

eg. Stock XYZ has been stable, priced at $100. It will soon pay a dividend of $1. When should the stock price first drop to ~$99.

At…
Option A: 4:00am (extended hrs open)
Option B: 9:30am (regular hrs open)
Option C: 4:00pm (after hrs open)

On…
Option 1: 2 biz days before ex-div date
Option 2: 1 biz day before ex-div date
Option 3: Ex-div date

Any evidence to support your answer is appreciated.