The shortest timeline to get a registered mark on the principle register is about 9 months. It typically takes just over three months from filing before the Trademark Office evaluates your application. If approved, it takes about a month and a half before it’s published for opposition. After that point it is eleven weeks before it registers, absent any opposition.
If the Trademark office issues an initial rejection of the application, it can add anything from a few days for a ministerial change to a few weeks for a more complicated rejection, though the deadline for a response is six months.
A good trademark attorney will keep the ball moving and aim to get your trademark registered as quickly possible.