Google sandbox question

Hi
It is said Google sandboxes a fresh domain for about 8 months. So does it make sense to just buy the domain, make quick wp page and let it rest 8 month and then build the real site?

it's not always 8 months... actually, it's not always sandbox, just sometimes (only google knows when, but I suspect that niches that are too competitive, or too profitable, or both, see the most sandboxes).

And it makes no difference what you do with the domain since you can't rank the site anyway while in sandbox. You can let it sit unused, or work on it, the result will be the same if you're sandboxed (you won't see any google rankings or traffic)

So when I let it sit 8 month and start working on it after the let's assume 8 month, is it starting the sandbox when it is worked on, or does it start when you buy it and register it? My idea is to buy some in bulk and let it sit and start working after the 8 month. Because expired domains are hardly available for my niche

It won't work that way
Google needs some data to figure out the niche and whether you deserve to rank on the first page