I often advise that any new site be at least partially developed in advance for a few simple reasons. I recommend doing this offline for a period while you figure out what your site is about, find your voice, find your writing style and perfect it, practice various SEO techniques, try more than one platform if that is necessary, and work with site decoration. Here are the major reasons for waiting to deploy a more settled site.
1] There is something for search engines to chew on when the site is deployed.
2] The inevitable self discovery process of any new site can at least settle into a niche/topic and natural keyword discovery can be done and exploited properly with SEO.
3] Allow experimentation time for various platforms/templates/features to be sure of the look and feel of a site.
4] With enough topics/posts, the new site can enjoy a certain amount of velocity that would not exist with just a few posts.
5] Take advantage of rapid spider/discovery/ranking of a substantial and fresh site rather than deploying a smaller site that then has to deal with lag times as a result of being a smaller site.
I have always advised that it is better to deploy a more mature site than deploy a starter site that then has to climb a steeper hill to get noticed and respected. Indeed many recommend that a blog have several posts before deployment. Some put this as low as 50-100 post, I say more if at all possible for the simple reason that search engines, Google in particular, get more excited about a larger site than a smaller site. Of course the site does not have to be fully settled in. I am not recommending that. But you may be surprised how many modifications you will make while your site settles in and you discover new ideas for your site. It is best to knock off the rough edges for at least one simple reason- user experience. You are far better off impressing your users than disappointing them. In that way, you will get more links and shares right away which helps your site gain rank and perform well in the SERPs.