It worked!

Work in progress (yes, it is as sticky and clumpy and hard to apply delicately as it looks):
Design complete and henna dry, now I’ve just got to wait a couple of hours:
And the end result:
That was after 2.5 hours (I was aiming for 3, but I forgot the number one rule of henna application: go to the toilet first!).  It’s a bit pale, but in theory, now that the pigment is in my skin, it should continue to darken, so should look better by tomorrow night.  I’m quite impressed, considering it’s my first attempt (the one I had done in India was done by a professional).
So now I just need to do the other hand…