Question:  After what date are additions to each club's playing list allowed for the 121st season of the Austrailian Football League (AFL)?

full_context: Document 1: 2017 Carlton Football Club season: The 2017 AFL season will be the 121st season in the Australian Football League contested by the Carlton Football Club. The club's women's team also contested the inaugural season of the AFL Women's competition, finishing fourth.
Document 2: 2017 Collingwood Football Club season: The 2017 Collingwood Football Club season was the club's 121st season of senior competition in the Australian Football League (AFL). The club also fielded its reserves team in the VFL, and a women's team in the inaugural AFL Women's competition.
Document 3: 2001 AFL draft: The 2001 AFL draft consisted of a national draft, a rookie draft, a pre-season draft and a trade period. The AFL draft is the annual draft of players by Australian rules football teams that participate in the main competition of that sport, the Australian Football League (AFL).
Document 4: 2017 AFL draft: The 2017 AFL draft will consist of the various periods where the 18 clubs in the Australian Football League (AFL) can trade and recruit players following the completion of the 2017 AFL season. Additions to each club's playing list are not allowed at any other time during the year.
Document 5: 2017 AFL Grand Final: The 2017 AFL Grand Final was an Australian rules football game contested between the Adelaide Crows and the Richmond Tigers, held at the Melbourne Cricket Ground on 30 September 2017. It was the 121st annual Grand Final of the Australian Football League (formerly the Victorian Football League), staged to determine the premiers of the 2017 AFL season. Richmond defeated Adelaide by 48 points, marking the club's eleventh premiership, their first since 1980. Richmond's Dustin Martin won the Norm Smith Medal as the best player on the ground. The match was attended by 100,021 people, the highest crowd since the 1986 Grand Final.
Document 6: 2017 JLT Community Series: The 2017 JLT Community Series was the Australian Football League (AFL) pre-season competition played before the 2017 home and away season. It featured 27 matches across 25 days, which began on 16 February ended on 12 March. For the fourth year in a row, the competition did not have a grand final or overall winner. The competition had a new sponsor in 2017, JLT Sport, replacing the National Australia Bank (NAB) after NAB elected to sponsor the inaugural AFL Women's season instead. All matches were televised live on Fox Footy as well as on the AFL Live app.
Document 7: 1997 AFL season: The 1997 Australian Football League season was the 101st season of the elite Australian rules football competition.
Document 8: 2016 AFL draft: The 2016 AFL draft consisted of the various periods where the 18 clubs in the Australian Football League (AFL) could trade and recruit players following the completion of the 2016 AFL season. Additions to each club's playing list are not allowed at any other time during the year.
Document 9: 2002 AFL draft: The 2002 AFL draft consisted of a pre-season draft, a national draft, a trade period and the elevation of rookies. The AFL draft is the annual draft of talented players by Australian rules football teams that participate in the main competition of that sport, the Australian Football League.
Document 10: AFL finals series: The Australian Football League finals series, more generally known as the AFL finals, and known from 1897 until 1989 as the Victorian Football League finals series or VFL finals, is a tournament held at the end of each AFL season to determine the premier. The top eight teams qualify for the finals based on the home-and-away season results, and finals matches are played over four weeks under the conventions of the AFL final eight system, culminating in the AFL Grand Final. The finals series is traditionally held throughout September.
Document 11: 2015 AFL draft: The 2015 Australian Football League draft consisted of the various periods where the 18 clubs in the Australian Football League (AFL) can trade and recruit players following the completion of the 2015 AFL season. Additions to each club's playing list are not allowed at any other time during the year.
Document 12: AFL pre-season draft: The AFL pre-season draft is the drafting of uncontracted players to teams in the Australian Football League. The draft is conducted after the national AFL draft and before the start of the next AFL season. It is conducted at the same time as the AFL rookie draft. The pre-season draft is a place for any uncontracted players to nominate that missed the AFL draft or who were delisted after the main draft. It was first held in 1989 and has been diminishing greatly in its importance; the last five years have only averaged 8 selections per year, compared to over 50 in each of the first five years. It was considered that the pre-season draft only existed to protect the league from writs for restraint-of-trade, but due to the introduction of free agency in 2012, there have been calls to scrap the pre-season draft and extend the free agency period.
Document 13: 2017 Sydney Swans season: The 2017 AFL season was the 121st season in the Australian Football League contested by the Sydney Swans.
Document 14: 2017 AFL season: The 2017 Australian Football League season was the 121st season of the elite Australian rules football competition. There are 18 teams competing in the league, the same as the previous five seasons. The first game was played on Thursday, 23 March, and the season concluded with the 2017 AFL Grand Final on Saturday, 30 September.
Document 15: 2014 AFL draft: The 2014 AFL draft consists of the various periods where the 18 clubs in the Australian Football League (AFL) can trade and recruit players following the completion of the 2014 AFL season. Additions to each club's playing list are not allowed at any other time during the year.
ground_truth: 30 September