I have a personal blog. To avoid looking like a spammer, let's call it, www.xyz.com. This is my personal blog and I have several categories listed on it.

I also have several other domains that I want to develop some day. They take the categories I already have on xyz.com and make those posts their own site with a niche focus.

So instead of this:

Personal Blog
Personal Posts
Tech Posts
Marketing Posts
Ranting Posts
etc.

I would have:
Personal Blog
Tech Blog
Marketing Blog
Ranting Blog

I have domains already registered for them and all that good stuff.

Now the question...

Since I have JUST started seriously blogging (I only have about 51 posts broken over these various categories), what should I do?

a. Continue to put everything on one blog w/ categories and when I have 50+ posts in each transfer them over to the niche domains

b. Disregard the low number of posts and transfer them to the niche domains now

--

Personally, I'm leaning towards option "b" because when it comes to registering these blogs for directories, etc, it's hard to do so properly.

Any thoughts?