I got a timesheet I want to advance the dates that I have listed. I don't know command to do it, and I am tired spending 15 minutes of manually changing it every time.
well, if i'me understanding your problem, if you just format a range of cells with your date format (or custom format with the format the way you like) and then say have a date entered in cell A1, then in A2 you would put =A1+1, etc and it would increment the day by one. then you only have to update the date in cell A1 to update all of them.
Another way, similar to the above, but Excel guesses correctly what you want!
Use the fill handle to do the lifting for you...
Excel will give you this example, Use the help box to search for "Create a consecutive list of dates"
Create a consecutive list of dates
Type the first day or date in the list, for example Monday or 6/13/08, in a cell.
Select the cell and use the fill handle (fill handle: The small black square in the lower-right corner of the selection. When you point to the fill handle, the pointer changes to a black cross.) to fill a list of consecutive days.
Note If the fill handle is not displayed, click Options on the Tools menu. On the Edit tab, select the Allow cell drag and drop check box.
If you want only weekdays in your list or if you want to display dates with monthly or yearly intervals, click Auto Fill Options and then select Fill Weekdays, Fill Months, or Fill Years.