2. Right after midnight on her birthday.
One Japanese woman in her 20s was deeply moved. “I could tell he was putting his heart into celebrating my birthday a memorable way”. You will have to stay up late and count down the minutes, but it will leave her with a good impression. Especially if she is counting down the clock herself, it’ll be a happy coincidence. The only drawback is that the likelihood of her receiving multiple messages at midnight is quite high, so try to be creative with your message so that it stands out.