Jowell had been scheduled to deliver a speech at the Edinburgh Television Festival on Saturday, but has had to pull out because a close friend has died.
The minister had been expected to give the go-ahead to the BBC's £300m digital plans, which includes the launch of two children's daytime TV channels, a youth channel, an arts channel and five digital radio stations.
However, when she does make the speech, she is expected to offer certain guidelines to the BBC, such as warning it not to compete with the commercial sector.
The BBC's plans have come under fire from commercial broadcasters, particularly children's channels such as Nickelodeon, about its proposals to launch into a market which is said to be already crowded.
The BBC owns many popular children's characters and TV shows, such as Bob the Builder and The Tweenies. Rival channels may feel threatened by the broadcaster's strength in this area.
BBC director general Greg Dyke is said to have been frustrated about the length of time the government has taken to reach a decision on the services.
The BBC has been waiting for approval for its digital services since the beginning of the year. The decision was first delayed until after the general election, then the government ordered a second round of consultation, delaying it further.
It is now believed that the channels will not launch until next year, although programme makers are said to be on standby to begin working on the services as soon as they are approved.
The BBC believes its digital channels and radio stations, which will all be free-to-air services, will help speed up the switch-over to digital, boosting the government's plans to switch off the analogue signal by 2010.