Hi,
There is no fixed time for orthodontic treatment (braces) as each case is unique.If there is space between the other teeth to accomodate the pushed back teeth the treatment will take less time.However if there is no space to push the teeth back space may have to be created by extraction of premolar teeth in which case the treatment takes longer.In either case you can expect anything between six months to two years followed by wearing of a retainer.The retainer is an appliance to hold the new position of the teeth.
Next Steps
Orthodontic treatment is the best long term option in your case.Though the initial period is awkward after a couple of weeks you will adjust to them and hardly notice them.
Health Tips
Hope that helps.