Unfortunately for men who want "instant" sideburns, it's impossible to grow in one area of facial hair more quickly than the rest. It is possible, however, to encourage all of your facial hair to grow in faster, with fuller sideburns the result. Because you have little control over how fast your hair grows, there's no one technique that will work on everyone. However, certain things will expedite the process.
Take vitamins A, B3, B5, B6, B12, C and D, and iron and biotin supplements once every day. These vitamins help stimulate hair growth and skin health. Many of these can be found in multivitamin products.
Clean your face with facial cream, moisturiser or exfoliating face wash. This will clear the pores, further assisting facial-hair growth.
Do daily exercises. A healthy body will produce hair much faster. Exercise can also reduce stress, which can cause hair to grow in weak and brittle.
Get adequate sleep at night. When you sleep, your body naturally recovers from the day's stresses. It's a time of restoration for your body and the time when your body grows hair the fastest.