I did my personality test mid-afternoon on Thursday, and got my email to say I'd passed Stage 1 around lunchtime on Friday so doesn't seem to take long to find out the result.
My best advice is just to be honest in answering the questions (although there are a few I had real difficulty deciding what to put) - you don't want to get caught out for being dishonest, and if you're really the right person for the job, you'll get through (at least this is what I've been putting my money on!).
Question - how long between sending off full application form and Stage 2 day? Am I likely to be seen before Xmas?