Create Postback Delay Client Side?

I am developing a web page where a user will submit some "Comments" on a form. When they click the submit button, I fire off some javascript that captures their current GPS location, which I store in a visible Text Box (for testing purposes). If the user is updating from a device that doesn't support gps, I add text to my textbox that says "Device does not support GPS".

When I get to the server, using a device that doesn't support GPS, that text comes through just fine. When I use my iPhone, I see the GPS Coords in my textbox, but that textbox value doesn't make it to the server.I'm thinking that there is a 2-3 second delay from the time that the button is clicked to the time that the java finishes retrieving the GPS. So the textbox text isn't set fast enough.I'm wanting to prevent a postback for 3 seconds (for example) to give the javascript time to update the textbox.