As simple as that procedure is, you CAN do it without even using the test light!  I use basically the same procedure and have never had any major timing related problems . . . and timing can cause MAJOR problems.  Give a few degrees too much advance and you might as well take a cutting torch to the tops of your pistons.  I've seen more than one set with holes burnt throught them because of too much timing advance!

Anyway, I just turn the engine over by hand to near where I want the timing set, pull the coil wire off of the distributor, turn the switch on, then slowly rotate the engine clockwise while holding the coil wire near a good ground . . . when the points open, the coil will fire and you'll see and hear (and if not careful, feel) the spark.  Back it up a little and try it again . . . two or three more times to make sure you know where it's firing.   Then, if necessary, losen the distributor slightly and adjust it.  Check/adjust/check/adjust until you get it firing just where you want it.  Lock down the distributor, check the timing one more time to be sure, plug the coil wire back in and you're ready to go.  (be careful of how long you leave the switch turned on with the engine not running.  If it sits with the points closed for more than a minute or two it can burn up the points and/or the coil.

The only time I use a timing light is when I suspect that the distributor is not advancing.