It's been a great success moondog. Several times I've wanted to post but it felt like bragging.
I honestly think DS2 understands morning afternoon and evening now independently of changes in daylight hours and we use it every day. It is positioned near the large timetimer in the kitchen (which DS2 also uses daily and spontaneously).
So, for instance, DS2's brother practices piano daily in the morning with my help. Ds2 gets jealous. I tell him that I will practice with DS2 in the afternoon. He then accepts that morning is DS1's practice time and watches peacefully (ish!). If I then sneak in a bit of DS1 piano time in the afternoon or evening, DS2 gets cross. He spontaneously runs into the kitchen to check the clock and verifies that the hand is not on the morning colour. He runs back shouting "it's not morning, it's afternoon. it's not time for DS1 to play piano".
I can use "morning", "afternoon" and "evening" to explain changes of daily routine that might otherwise bother him.
As a bonus, he can tell the time to the nearest hour (because he knows he must look only at the small hand - why don't they do this with all kids I wonder?) and has generalised this to all clocks with clear numbers. So if we sit in a cafe and it's 2.25pm he will spontaneously look at the clock and say "it's two o'clock in the afternoon - when it's 3 o'clock, we'll get DS1" (we leave to get DS1 at 3.10pm).
If it's 9.15am, I can say "when it's 11 o'clock, we'll go to soft play" and instead of running to get his shoes (as he would have done before) he looks at the clock with anticipation and says "it's 9 o'clock now, when it's 11 o'clock, we'll go to softplay. From about 10.40am , he will start announcing that it's 11 o'clock and therefore time to go (which is quite helpful - means we're on time).
I can imagine a commercial version that included "nighttime" - nighttime would be represented by a dark blue circle outside the main circle. It would have just one hand that would perhaps "stretch" when nighttime began then contract when it went back to the inner daytime circle.
Problems of course arise if a child doesn't sleep 12 hours a day (it's happened to us once when he got up at 6.30am). It wouldn't be suitable for a bedroom without the additional "nighttime" function. Kitchen (or classroom) is perfect though.
To give you a sense of his foundational skills - he still really only has "ownership" of "what" and "where" questions. "Who" is context-reliant though getting better, and "how" and "why" are a long way away.
But now he has such a concrete grasp of "when", I can ask and use general "when" statements and he understands them well. "When Oliver comes, we'll have a snack". I strongly suspect he "sees" the clock or the timetimer or the calendar in his mind as he listens to my "when" statements. He spontaneously says "when I'm 5, I'll have a birthday party and go on a train ride". The calendar has taught him to anticipate.
Interestingly, my brother (similar traits) spontaneously taught himself to tell the time at 4.
Now when I see the ghastly "tell the time" toys in the early learning centre catalogues, I want to scream at them saying "why are you deliberately trying to confuse these kids?". I may contact ELC with a proposal!
I truly believe that a child who can use the calendar, timetimer and clock can get a good or superior grasp of time concepts even with receptive language problems. Time is life's biggest unvarying certainty so must be a wonderful thing for our kids to master.
Next step for me is to coordinate the days-of-the-week colour coding that nursery has introduced (well-done nursery) and "map" these with highlighter pen on to our calendar......