The -q option is for retries in sending the mail. It will try immediately to send the mail, and if it could not, it would try again at the interval you set in -q. If -q isn't set, then it tries only once, immediately.
If sendmail is running on the system, it might be that if you used -q in the command and it failed to go, that the normally running sendmail process (one started on boot) could grab the message later to attempt to send (Not positive on this point but my testing shows this to be true - I disabled DNS to insure the email could not go but then the normally running sendmail will try every 15 minutes to send again).
If you don't want to send the mail now, then putting in a sleep command or scheduling an at job in a minute from now might be what you would want to do. Looking in the mailx and sendmail programs, I found nothing to delay sending a message. Possible that some other mail client could do this (like pine)
Added note: This may be something to help you out but would be changing how you send all mail possibly.
local versus remote mail