Mikveh time should be before dawn, meaning before the sky change colors from black to bluish.

The first four is from the Holy Ari (see text image from the writings of the Ari.).
The fifth dip and meditation is from the Ben Ish Chai. It connects us to Keter of this night. It’s the YHVH with the nikud of Kamatz that is related to Keter.
Mikveh times for few cities in the world.
Jerusalem, Israel – Before 4:08 am
New York – before 3:42 am
Los Angels – before 4:13 am
Miami – before 5:11 am
Toronto, Canada – before 3:43 am
Sao Paulo, Brazil – before 5:29 am
Rio De Janeiro, Brazil – before 5:15 am
Paris, France – before 3:21 am
For other locations check on https://www.myzmanim.com
Those who are not close to a mikveh and for some reason do the Shavuot connection at home, they can take a long shower with the same meditation. (Do not take the meditation note into the bathroom at home,unless the shower is isolated from the toilet.)
If you print the meditation, treat it as sacred names and dispose with other sacred text.
Chag Shavuot Sameach
Zion