How long does bell's palsy typically last?

It varies. Healing from bell's palsy can vary considerably. It may take only a few weeks or many months to recover. Most people will recover fully but some people will have permanent weakness or paralysis.
Three-> six months. Recovery from bell's palsy usually begins about 3 months after onset. Full recovery may take an additional 3 months. If you see no recovery at 3 months you should see a neurologist for an EMG of the facial nerve. Bell's palsy from lyme's disease requires treatment of lyme's disease, but the recovery also takes time, as there needs to be regeneration of nerve myelin.