hi zuz,
we always use either 4 minutes from overhead the beacon ( so thats 1 minute each leg and 1 each for the two 180 degree turns...or better still and more accurate 3 minutes form 90 degrees abeam the beacon ( remember if you are setting off for drift that has to be taken into accoun when calculating the 90 degree position )..on the outbound heading +/- drift correction...therefore 1 minute ( depending on the wind correction ) out, 1 minute for the 180 degree tuirn ( 3 degrees per second rate 1 turn ) and 1 minute for back to the beacon..
ok..hope that helps...
the dean