Comment on Google Sandbox Penalty by teo.
I don’t think that Google has a sandbox these days. I have a lot of new sites(3 – 6 months) that rank in the top 10 results for high competition keywords. I make hundreds of links every day for all of my domains and i have no problems at all because the links are not indexed the same day.
Also (New Sites = Poor Results) that became known as the Sandbox effect and had controversial definitions, does not exist anymore (in my opinion). Matt Cutts confirmed the sandbox existed, somewhat, in his Coffee Talk with Brett Tabke 7 years ago. But since then, they did not discuss it much.