You apply for the 820/801 at the same time, you can't skip applying for 820. If you fulfill the requirements for a long term relationship (at least 3 years as defacto/married or 2 years with a child of the relationship) and have sufficient evidence covering the entire length of your defacto/married relationship (note that periods of dating do not count), the case officer may choose to grant the 801 immediately after 820 is granted.
Thank you very much for the reply

so basically its up to the officer if he will grant the 801 after the 820 is approved correct? So the waiting period would be the 2years once the 820 is done?
Well now we are married 1year.. when we will be applying we will be married for 1.5years but our baby once we will apply will be 1year and 4months old...
The defacto relationship means what? As my fiance or living together?
We rented a flat out from 1.3.2016 I was living there for a month or two alone then my girlfriend in that time moved in... we then rented out a bigger flat together in 1.2.2017 and in 18.3.2017 we got married and living in the bigger flat since till we will pack up and fly to Australia together...
Thank you very much for any help and better understanding ??