I'm not starting the brew until late next week, but so far my thoughts are this:
- initial fermentation with kit and malt filled up to the 20 litre mark (to avoid the explosive head - oo err)
- attempt to keep as close to 21 degrees as possible
- after 3-4 days and when the brew has settled a bit, top up to the 23 litre mark. Should I give it a good stir now?
- leave at least 10 days and until I get 2 identical readings
- prime with 1/3rd tea spoon of granulated sugar in the 500ml bottles, a tea spoon in the 1.5 litre PETs and fill leaving about two inches (to minimise risk of bottle bombs - having said that hopefully this shouldn't be a problem if I have let it fully ferment out

- use my lovely shiny crown capper and caps, hoping they fit!
- leave for another 7 days at as close to 21 degrees as possible.
- condition for at least a month, without touching

- drink responsibly, ish.
Does this seem reasonable, or have I missed anything important / said anything daft? Is there any point taking an OG, given that 3-4 days later I'm gonna putting another 3 litres of water in there?