Marc Webb believes any proposal to introduce AFL reserves teams in the WAFL - no matter the format - must be resolved by the end of this month or abandoned for 2013.
Saying that all WAFL clubs had started planning for next season, the Claremont coach said it was the last feasible date for changes to the 2013 competition.
Webb will remain in charge of the Tigers next year after the club this week extended his initial one-year contract to the end of next season.
"It is almost too late to make changes for next year because clubs are already looking at contracts and their recruiting and retention strategies," Webb said.
"No matter what decision is made about the shape of the competition, certainty is the most important thing for the coaches and players.
"My biggest concern is that we may not have a decision until the end of the season which would put all clubs out of whack as they plan for next year."
West Coast and Fremantle have virtually abandoned their proposal to use the weekly WAFL bye to pit their reserves against the bye team, but have produced an alternative model in which they would play scratch matches against each other for the first six weeks next year.
That plan could see 30 or more players removed from WAFL ranks for the early part of the season, while amateur and country footballers would be used to top up the AFL reserve teams.
"If that happened we would deal with it, but we would still like to know about it as early as possible so that we could make suitable arrangements to cover the loss of those players," Webb said.
WA Football Commission chairman Frank Cooper, chief executive Gary Walton and football affairs committee member Brett Fullarton will visit the WAFL clubs in the next few weeks to further discuss the various reserves proposals.
The WAFL presidents met this week with the only concrete development being a unanimous stand against any club entering a host club alignment with either of the AFL teams.
However, neither AFL club appears interested in a host club arrangement like those that operated in 1999.
South Fremantle president Haydn Raitt said the clubs would be happy to meet the commission group in the coming weeks.
"We are all happy to go through the process as requested by the commission," Raitt said.
Peel's Trevor Williams is a coach in a lonely category, with his tenure for next season remaining in some doubt.
East Perth's Tony Micale and Chris Waterman, from Subiaco, are set to take up options to continue, while Swan Districts will soon start the process to reappoint Greg Harding.
Damien McMahon's bid to end Perth's decades of mediocrity and lift the Demons from the bottom of the ladder received a pre-season boost when his contract was extended to the end of 2013.
Steve Malaxos is the only WAFL coach not on contract due to his status as a full-time East Fremantle employee, but the former premiership captain has the Sharks poised for September action.