Braces can definitely improve flared teeth. Again, how soon this will happen depends on what your initial alignment looked like.
If your teeth are flared out because you have gaps in between your teeth, then improvements can be seen quite early (see the case below).
^1st month of treatment
^4 months of treatment
^9 months of treatment
If the flaring is due to overcrowding, then you and your dentist may have chosen one of 2 treatment plans:
A) Non extraction: May be suitable for patients with a nice side profile, mild crowding and no major concerns about flared incisor teeth. This type of treatment may increase flaring of the incisors to gain space to relieve the crowding.
B) Extractions: This is suitable for patients with protruded lips, more severe crowding and flared incisors.
If you have chosen plan B, then it will take time for the treatment to progress to the space closure stage, which is usually done AFTER the teeth have been more aligned. This may be what your dentist has been working on after starting your treatment.
Bring up your concerns about how your treatment is progressing with your dentist since they would have a complete understanding of your initial condition and your overall treatment goals.