I have a slightly different look on that (and I have only written a cue point on a CD sleeve once – Ease On Down The Road … very long and boring intro :-).
I look at what a track does, if people enjoy it … I wait til the outro comes. If they seem a little bored or confused by the track, I will do a transition halfway. In other words if you are counting, you know when the next possible (8 bar) phrase starts and if you know your tracks well enough, you will know where breaks, drops and other significant moments are about to happen.
If you are just starting out, I guess it would help to write down a few good mix in mix out points. However, I doubt I would use time. First because you will have to keep a close look at the timer, you have to make sure you wrote down the time remaining or time played time and that it coincides with the time shown by the player (always time remaining for me) and secondly because you get lazy and stop counting. If you were to write down Track A: after first break, then you’d be forced to count while you listen to your track. You have to notice, hey this is the first break, so at the end of my 7-2-3-4, 8-2-3-4 I have to start the other track.
This way you will automatically practice counting and understanding track formats while playing. It’s good practice, imho.
Greetinx.