M.H.
All babies are different. My first slept through the night @ 6 weeks and the second didn't make it through the night until 3 months old.
I am sorry to say it's possible he won't be sleeping through the night when you go back to work so I would prepare yourself that it's a possiblity. Be flexible because his sleep patterns will constantly change as he gets older. Cereal in the bottle is what helped my kids. It might make him sleep a little longer so you only have to get up once or twice verses two or three times.
Good Luck!