I'd say you take the test whenever you feel most prepared - no sooner. That will probably be, in terms of practice time, very different for each person. I'm not sure where lawschooli.com got their info from, but there are plenty of people - myself included - who have continued to score higher, more consistently with more time. I actually read somewhere that some LSAC rep said he recommends at least 6 months of study.I spent about 2 months drilling technique/method until I was consistently scoring 180s on un-timed tests. I did not plan that, it just so happened to take me that long to get there. I then took 2-3 months to transition into timed tests and then another 2 months to transition to exact test conditions. By test day, I had taken just about every single test available and did not run out of tests. Remember, you MUST review every single test - in some cases multiple times.I ended up scoring within my average LSAT PT band - albeit in the lower end of it.Good luck!
Going from 147 to over 170 is ambitious to say the least. I'm not saying its impossible - but you may find a month to be a little bit of a time crunch. If you truly think you can do it - id consider post-poning the test until February, or even June. If you don't think that is realistic, then take the test when you feel completely ready...Good luck!
I agree with Miami and hopefully you get a 170, but that is in the top 10% of LSAT takers and those who actually show up to the LSAT are college graduates that are motivated enough to get into law school. So it is the top 10% of tough competition. Additionally if your diagnostic was 147 odds are with proper studying you can get between a 154-158, which is sufficient to get admitted into an ABA law school. If you get an ABA law school you can succeed as a lawyer and 90% of active lawyers did not attend the top 10% of law schools. Do everything you can to score as well as possible, but do not get to discouraged if you score under 170. Almost every LSAT taker does. Good luck with the test.