I've read a bit about buying old domain names, developing them for a bit and then 301'ing them to a new domain with a name you want. I realize that there are some that think this works and some that think it doesn't. For the purpose of my question, I am assuming that 301'ing actually works to transfer the weight of the age/rank/whatever of the older domain to the newer domain.
My question: I have already started a 3 month old site that is clearly sandboxed from my desired search terms. I intend the site to be a long-term site. I already have a number of backlinks to my new site and several pages have been indexed. Is it too late to use the 301 strategy?