What do you mean by "standard" solution? "Standard" as per your shop? If so then how are we, who do not work there, expected to know the answer? Otherwise there is no such thing as a "standard" solution. Most places will use a business date dataset to get the date to be used and will use the ACCEPT TIME, or similar for other languages. If you really need the job start time then you create your own program that will step through th control blocks for your job as stated above. Or you could have a small program at the very start of your job, before any housekeeping, which will get the current time and store it.
The problem I have is that people can explain things quickly but I can only comprehend slowly.