About 1980
Seriously, John's suit was made well before ROTJ so don't go copying anything if you want to make an ROTJ replica. The strapping is totally different inside but he plastic armour components are virtually the same. It's the helmet that differs the most. The shape is different as is the interior.
If you want to build a good suit, use movie screen caps or photos of real armour. CRL's are a good base to work from but not very accurate in my opinion.