Hi Sami,
Well i did everything by myself. Yes thats right it could take even more time.
First stage - Engineers Australia assessment that could take upto 19 weeks (5 months) according to current processing time. (It takes lesser time if you applying through Washington / Sydney accord (1-2 months)
Second stage - Invitation based on EOI process may take 2-3 weeks based on the date of application cuz there are 2 rounds every month)
Third stage - Visa application 10 weeks maximum, in my case around 8 weeks for independent visa subclass 189 (subclass 190 will take lesser time but i think if he has the same ANZSCO the job is N/A in the SOL, 190 state sponsorship process is faster)