[fisf]

A person proficient in multiple programming languages absolutely knows all of the 6 concepts - it's just cases of 'aha, go allows me to do x,y,z and this is how things should be done'.

I basically learned ideomatic go in a week, by skimming over the "effective go" guide and cross referencing concepts to other languages I know -- there is really nothing inherently 'new' in Go that would require years. It's a deliberately simple language.