Don't use that method. Its rather unreliable and also very slow. The best way to calibrate is to estimate a range of possible delays. For diamond, platinum, and soulsilver I consistently get 14 seconds. In ss I get between 486 and 500. Use time finder and just go for any seed within that range. After you hit A at continue, imediately open the pokegear and start calling elm, marking his responses, just like you would mark coin flips before. that's the best way to find your delay and time since, as you said, most wild pokemon in hg/ss are too low for proper validation without rare candies.
