Traffic during the week by car is busy. However, if you leave before 7am, it's flowing traffic. The B-line bus service is amazing. It runs ever 5 or so minutes and can get you to Neutral Bay in about 20-25 minutes for a quick change onto a North Sydney bus.
I travel into the city each day - it's a 1 hour trip for me, including a kindy drop off in Brookvale.