Reader Tim Biggio is hampered by the punishing policies of his Internet provider. He writes (and I rant):
I live where there is no DSL or cable available so I have to get my Internet via satellite. The downside is that they limit downloads in any 24-hour period to 500MB. This is fine for regular activity, but when my computers need software upgrades it jumps over. The penalty for exceeding is you are limited to 56K speed for the next 24 hours. The possible upside is that I get unlimited downloads between 2 AM and 5 AM. Is there a way to have the automated software update run in that 2 AM to 5 AM CT window?
Ah, another satisfied Hughes satellite customer. Very briefly donning my editorial hat, in an era when these kinds of massive updates are common on both the Mac and Windows, it's shameful for Hughes to continue this policy. As a former satellite broadband user I can testify that this means of using the Internet is painful enough without your ISP standing over you like an abusive parent.
Okay, now to your issue. Although Software Update allows you to schedule daily, weekly, or monthly updates, it doesn't provide an obvious way to schedule a time for the updates to occur. But there is a way. And that way is to manually check for updates at the time you want future automatic updates to take place.
When you open the Software Update system preference and click the Check Now button, you set the time for the next automatic check. So, for example, if you click this button at 11:45 AM and you've configured Software Update to check for updates weekly, it will check again a week later at 11:45 AM.
I could suggest that you spend some quality time with the Late-Late-Late Show, stay up until 2:01 AM, and click the Check Now button, but this is something you can deal with in the daytime. And you deal with it by opening the Date & Time system preference, unchecking the Set Date & Time Automatically option, entering 2:00 AM in the time field, launching the Software Update system preference, and clicking Check Now. You don't have to accept any of the updates. Quit System Preferences and relaunch it. Return to the Date & Time system preference, enable the Set Date & Time Automatically option to get the correct time. Software Update will continue to believe it should check for the next update at 2:01 AM.
If you're the kind that cares to geek out, you can also edit the com.apple.scheduler.xxxxxxxxxxx.plist file, which you'll find in ~/Library/Preferences/ByHost. Open this file in Property List Editor (part of Apple's Developers Tools) and you'll find a date field under the Timer heading. You can edit this date to rejigger the scheduled update time.
This story, "Scheduling Software Update" was originally published by Macworld.