I think the jambette is the exercise that is the nicest, easiest and usefullest of the 'stretching'-things. You can build it out on so many ways, spanish walk, trot, polka, and maybe even the galop on three legs or pirouette with one leg high.
I'm learning it to Missy now, just started with it one time, and she immediately understanded what I ment. I touched her leg (low), she lifted her hoof a little bit, I 'clacked' with my tongue (that's my clickersound) and gave her a piece of carrot.
After 5 minutes, she knew that if I point to her hoof, I ask her to lift it.
It's not really stretched at the moment, only the lifting, but when you only reward your horse for the stretching-moments (when she know the cue well), she'll understand you very soon..
I think it's nice to change the cue to mimickry at a later moment, but now I started with 'pointing', and I think it's a little bit confusing for her to have two cues, to be honest..
I'm not very experienced at teaching horses the Jambette, Missy is only my 3th horse (to teach it), but if I were you, I would choose one cue for it, so that it's clear for her what you mean, and you can ask it quick for her, instead of having a whole ritual of touching and lifting your own leg.
(But I would like to read some other opinions from the more advanced in this. Because this is only a tought from me, I don't know if it's true what I'm saying
Succes with this nice exercise!