If the executive committee decides in December on a 2000 start rather than 1999, "I think the clubs would have to live with it," Aigner said at the end of a special Uefa meeting.
Last month representatives of major clubs agreed not to join a breakaway Super League after Uefa proposed changing its Champions' League, offering teams more money.
Uefa promised to expand next season's League from 24 to 32 clubs, playing in eight groups of four teams in the first stage. It also proposed to merge the Uefa Cup and Cup-Winners' Cup into one competition, called the Uefa Cup. Leading clubs want the new competitions to begin next season to maximise potential earnings.
"There were some reservations about an early start," Aigner said. Uefa stressed that both revamped competitions would have to start the same year. The 17 dates needed to stage the new-look Champions' League in an already tight season could prove a problem for some of Europe's larger leagues.
Uefa presented to associations two alternatives for the new Uefa Cup, one of which would see eight teams who did not qualify from their Champions' League group joining the competition in its third round. "The feedback that we get is overwhelmingly positive for that move," Aigner said.
The wealthier associations favoured a group stage in the Uefa Cup, but smaller federations backed a straight knockout format, he added.
In other business, Uefa members agreed a memorandum backing its regulations to prevent two or more clubs owned by the same company taking part in the same European club competition.
In July, the Court of Arbitration for Sport provisionally suspended the regulation, ruling that Uefa had not given clubs enough time to adjust when it was introduced in May.
The ruling came in response to an arbitration request from the Greek club AEK Athens and Czech club Slavia Prague, both controlled by the British company ENIC.
The associations "reaffirm our unqualified support for the Uefa rule, and the sporting principles which underlie it," the statement said. They also agreed to lobby the European Union for an anti-trust exemption to allow Uefa to market television rights centrally.
"Unless a means to redistribute income is recognised, there is a real danger that the existing disparities between the rich and poor will become a yawning gulf," they said in a memorandum, adding: "The marketing of competition matches by individual clubs will inevitably disrupt the league structure, as investors would focus only on the best teams."Reuse content