Hi Rachel,
I was "full dose AA, low dose E" for about 18 months before ramping up my E dose, and I'd highly recommend it if you're wanting to keep things under wraps for a while!
From my experience, the rate of physical changes is proportional to your estrogen levels; if you keep your E levels low, you probably won't get too much happening, although your skin will probably become a lot smoother / less oily (one of my docs told me that skin texture is actually one of the most dimorphous secondary sex characterisitics in humans).
For me, though, the impact of lowering my testosterone was huge, and for that reason alone, I'd say go for it, as long as you're comfortable with the effects that AAs will have on your libido, etc. I will always remember the morning I woke up, about three days* after starting HRT, and realised that the "noise" I'd had buzzing in my head for the last sixteen or so years had finally gone. It was a truly magic moment

* I will add that I take cyproterone acetate, which is a very powerful AA. Until recently, I'd been taking only half of the "low" standard dose quoted in many places, and my doctor has just cut my dose in half again -- in her words, if I were a cis-female, she'd be concerned that my T levels were too low!