You're right I am nervous about it but I appreciate that - I'll leave it alone.
I'll test it next week, perhaps 7 days after putting in.
Does the 'head' drop to the bottom indicate it's finished doing its thing?
Leave it alone for 13 days. Day 13 take a reading. Day 14 take a reading and if consistent, bottle. I pretty much only take 3 readings now. Day one before pitching the yeast and then as described.
Anything with a lager yeast, 3 weeks then bottle. Take a look at the kit brewing sections of jims beer kit forums, excellent source of information