The Date & Time button on the Graph toolbar runs a script in the [DateTime] section of the STANDARD.OGS file. That script consists of
label -s -sa -d (.6*page.width) (.05*page.height) -n timestamp $(@D,D10);
The $(@D,D10) is the key to customizing the format. In this case we are asking for the 10th (numbered from zero) date format from the Origin Date Format list (which is M/D/YYYY HH:MM:SS).
In your case, getting the precise format you want could be quite complicated. For an example that doesn't deal with the 'leading zero' issue, try:
%A=$(@D,D11);
%B=January February March April May June July August September October November December;
%M=%[%A,3:4];
month=$(%M);
%M=%[%B,#$(month)] %[%A,5:6]/%[%A,1:2];
label -s -sa -d (.6*page.width) (.05*page.height) -n timestamp %M;
Consult Substring Notation in the LabTalk manual (page 14) for other options.
** Origin Tip **********************************************************
* Check to see if Origin uses a LabTalk script for a tool or menu: *
* (1) Open the Script window by selecting Window:Script Window *
* (2) Hold Down the Ctrl AND Shift Keys (just Ctrl for 4.x) *
* (3) Select the menu option you want to test *
* If the option runs a LabTalk script, that script types to the Script *
* window, but does not execute. *
* *
* You may see something like: *
* run.section(GRANALY,LowPass) *
* which opens the file named GRANALY.OGS and runs the script in the *
* [LowPass] section. *
************************************************************************