You should perform two rakat as Tahiyat al-Masjid and then 4 rakat as Sunnat Muakkadah before Fardh Salah of Jumuah. After Jumuah, first perform 4 rakat Sunnat Muakkadah and then two rakat Sunnat. Then, you should go to office. The later Sunnah salah may not be offered before Jumuah.
Allah knows Best!
Darul Uloom Deoband