"Station Names - Dates of Opening, Closing and/or Change of Name" has Tuggeranong opened 1887-12-08 and closed 1975-03-09.
I'm suspicious of the opening date, as that's the date the line opened from Queanbeyan to Michelago. Michelago received the next station number for that line (as did every other station except one to Bombala, if it opened with the line), but Tuggeranong and Rob Roy/Royalla didn't!Queanbeyan - Michelago opened 1887-12-0840G
Tuggeranong (opened with the line
Rob Roy (opened with the line
, renamed Royalla 1905-10)40GB
Williamsdale (opened 1891-08-29)40H
Michelagoline opened to Cooma 1889-05-3140I
Billilingra (opened 1894-10-18)40K
Umeralla (renamed Chakola 1921-04-01)40L
Coomaline opened to Nimmitabel 1912-04-2040P
Rock Flat (out of order because ???)40N
Dalkeith and Baker's Siding (opened 1920-08-27, renamed Bobingah 1921-08-22)40Q
Nimmitybel (renamed Nimmitabel 1912-10-27)line opened to Bombala 1921-11-2140QQ
Maclaughlin Siding (opened 1939-05-02)40R
. Other lines used the "O" suffix.