GFCI receptacle install

I have installed many gfci receptacles. I know that if installed first from breaker, downstream rec. will be protected. Is there an easier way to locate the first rec. other then disconnecting what you think is the first and verifying?

Wiring has resistance or "ohms"

The further away from the breaker panel you get, the more resistance in the wiring there would be.

A safe way to check this would be to measure the resistance in the ground wire from the breaker panel. Turn off all the power in the house to be safer.

Connect a long wire like speaker wire or whatever (cheap wire for testing only) to a screw on the cover of the breaker panel (ground). Then run this wire to where the outlets are located.

Then test for resistance from the wire you have run to the ground connection on each outlet for that circuit.

In theory the outlet with the least resistance (ohms) would be closest to the electric panel so far as the wiring goes*.

Following is a google search of how to use an ohm meter. Some of these pages are written for Einstein. Skip those until you find something simple on how to easily read ohms using a multimeter.
http://www.google.com/search?hl=en&source=hp&q=how+to+use+an+ohm+meter&aq=f&aql=&aqi=g-s1&oq=

In some cases wiring will go to an electrical box which has another circuit and all grounds are tied together. If the circuit is like this, then this method may not work.

Any device wired to the "load" screws on the GFI will be protected. Pushing the "test" button should turn off any device attached in that fashion. You can also buy a GFI tester that plugs into a receptacle.