Best way to get ready is to have the game downloaded.
'The Sims 4' is due out in just a few days, and for fans who have already pre-order (or wish to pre-order now), Electronic Arts has a nice little bonus eature, pre-load.
From EA, "Pre-load is currently rolling out for everyone who pre-ordered the game on Origin. When it's available in your area, just launch Origin and download your copy. You can check to see by hovering your cursor over the game tile in your Game Library."
Fortunately, in this case, there is a little more detail than that. For those in the US, the game will unlock on September 1st at 9PM PDT (September 2nd 12AM EDT).
Outside of the US< the schedule goes like this:
September 2: North America, Central Asia, and Russia September 4: Australia, Japan, and Europe (excluding the UK) September 5: New Zealand, India, South Africa, and the UK
For those interested, but still unsure, EA has a 'The Sims 4 Create A Sim' Demo, which can be downloaded here.