How long before the game starts do the teams have to advise firstly there 19 (I think they initially drop 2 off ??) and then the final 17 players to take the field?
OT, here is the NRL explanation article:-
https://www.nrl.com/nrl-team-lists-announcement-changes/tabid/10874/newsid/104101/default.aspx
In 2017, NRL.com and the 16 NRL clubs will announce squads of 21 players at 4.00pm on Tuesdays, with 19-man squads named 24 hours prior to kick-off for every match.
Official NRL Team Lists
The team lists process was reviewed in the off-season with a goal to recommend the optimal future system for NRL matches.
The aim was to improve the accuracy of player information, including correct positional data, and to limit any potential integrity risk to the game through an improved team announcement procedure.
Every Tuesday at 4.00pm Sydney time, NRL.com and each club will announce a 21-man squad consisting of 17 "Active" players named in position, with a maximum of four additional players named as "Reserves". (The Warriors squad will be released at 3.00pm Sydney time [5.00pm Auckland time] on Tuesdays.)
Then 24 hours before each game kicks off a 19-man squad, only from players included in the initial 21-man squad, is selected with 17 "Active" players named in position and a maximum of two additional players named as "Reserves". For example:
• Wednesday 8.00pm announcement for teams playing at 8.00pm on Thursday
• Thursday 8.00pm announcement for teams playing at 8.00pm on Friday
• Friday 7.30pm announcement for teams playing at 7.30pm on Saturday
• Saturday 4.00pm announcement for teams playing at 4.00pm on Sunday
Then one hour prior to kick-off a final team of 17 active players is confirmed, only selected from players included in the 19-man squad.
Clubs wanting to bring in a player from outside the 21-man squad or the 19-man squad after they have been announced must apply for an exemption which will be evaluated by the NRL's Head of Football on a case-by-case basis.
Other Rules:
• Players named as "Reserves" on Tuesday will still be able to be named in the starting sides of NYC and NSW/QLD Cup
• Any players included in the 19-man squad will be deemed ineligible for selection in the final 17-man squad if they play in a NSW/QLD Cup match prior to the NRL match
• In each squad announcement, coaches are to endeavour to name teams with players in correct positions
NYC team lists will follow the same process, but their squad sizes at the three announcements are 23, 20 and 17 players.
