After how long arrest we can go for independent breath test

You can go at any point after being released from custody. But obviously the longer you wait, the less the result will be relevant. You should definitely speak to an experienced Charlotte DUI/DWI lawyer to figure out what defenses you might have to the charge. Ive attached a video about what rights you have when asked to provide a breath sample for your convenience.

The sooner the better. You could also have a blood test performed.

As long as you still have alcohol in your system but obviously the sooner the better.