Well I hope you do get it before weekend. If you are going to try for maximum depth in your test garden then may I suggest the following.
Get the machine put together, walk in back yard, turn on and run sensitivity all the way up in All Metal mode. Hold the machine rod so coil is waist high and parallel to the ground. Check to see if there is any interference noted with coil at waist height. If yes lower Sens down to quiet it.
If not find a piece of ground free of targets. Bobb the coil from 1 inch to 10 inches above ground several times and listen for any audio reports, or any phantom responses on the screen which are generally negative numbers. If no response then swing coil back forth over a target free area to see if the machine responds to the ground. If yes lower Sens until it doesn't. Now conduct your tests.
If you head to another geographic location repeat the above procedure. It will help you set the Sens as high as possible, with one caveat, in high trash areas turn it down to get the best response.
HH
BarnacleBill