Cut the tip of my pointer finger off 8weeks ago. How long does it take to heal? How long will it be sensitive.

Maximize healing. The real question is what not to do that slows down healing. Avoid using alcohol, peroxide, hibiclens, betadine, and bleach solutions. Inflammation ( red, hot, swollen, tender) is important to healing so anti-inflammatories (motrin, advil) are bad. Cover the area with a clean dressing changed every other day and protected from trauma. Antibiotics do not help healing unless it is truly infected.
Depends. The time for healing depends on the size of the defect, how much skin was lost. It will be sensitive for quite a while, often for months, but should eventuall be fullly useful.