I'll take your word on it for 3rd March, as I don't have any source that would give me an exact date, but that would seem very likely, and certainly they would have wanted singles and albums out before the UK and Europe tour started in the middle of the month.
presumably the 3rd March 1967 same as the first 3 singles?
MEMPHIS GOLD VOLUME 1 STAX 589001 was the first, picked up recently must get round to putting it up.
1966 is only the copyright date here, relating to the original US release. The Stax label wasn't launched in the UK until March 1967, see Billboard, and judging by the catalogue number, this was one of the first issues, so likely to have been released that month.