You should wait 8 weeks between treatments. Generally, the longer you wait between treatments, the better the clearance of ink. The added time allows your immune system to move the ink away from the tattoo.
There are patients who want their treatments spaced as closely as possible. While this may work for small tattoos in patients who heal quickly, it's not a good idea on large tattoos or for people with an ink that's resistant to treatment. Large tattoos require more time to heal and the more ink there is to be absorbed, the longer it will take your body to do so. Some studies have shown that the more time between treatments, the faster the removal. Learn more here: https://masterpieceskinrestoration.com/laser-tattoo-removal/