Your first visit to an orthodontist should be at the age of 7. At this age it is still usually too early to start with an orthodontist therapy, however, it is the right time to see when and what kind of therapy will be needed in the future.
It is also the perfect time for a myofunctional appliance therapy. Early therapy can help eliminate unwanted habits, speech difficulties, have a beneficial effect on jaw relationships, all of which makes the therapy at a later stage easier and shorter.