There is no way to specify a "send time" when you set up the standard merge.

It might be possible to specify a send time if you use a macro approach
rather than mailmerge to do your mailing (see the http://word.mvps.org site
for articles that might help you there) but I rather doubt it

You would probably be better off tryuig to use the standard Windows
scheduler - see Control Panel|"Scheduled tasks" - to start a Windows
batch/command file that starts Word with a particular document and/or macro.
Not something I have done yet.

Peter Jamieson