If it's an online venture better to get a prototype or proof of concept ready before spending on registration.
I just saw that this question hasn't been answered for 7 months and thought I would share my opinion, so you have at least something to go on. If you are thinking to get your company registered, you should register it instantly. You can make all the business plans in the world but unless you try it out to see if it works, you'll never know! Business is fast paced, chances are your b-plan is already outdated by now but I hope you went for it or will register it momentarily.
I by no means am an expert, but I take from the school of thought that there is no real reason to get your company registered until you start gaining revenue. In fact, I'd spend some time finding out what exactly your audience is looking for before even going any further. It's too easy to assume we know what people actually want instead of asking.
I'd check out Malcolm Bell's blog on how he used a survey and a landing page to get over 10,700 users for Mailcloud in 5 weeks before even creating the prototype (http://malcolmbell.net/2014/02/28/my-mailcloud-app-10000-users-in-first-2-weeks/). Bell will give you some great ideas on how to start your business on a dime.