When to make the leap: employed to freelance within same industry

Hi all,

I'm new here; not a freelancer yet but seriously considering making the leap this year.

I work in medical communications/medical writing with about 6 years' experience. I have some more general questions I'm hoping people on here can answer, though hoping to find someone in my industry who freelances and I can have a chat with.

-When to take the plunge? I have a 3 month notice period and was thinking about waiting until after a session I've booked with a financial advisor (not just for freelancing advice but related) which is in about a month's time - then I'd have a better idea of the situation. Anything else I should consider?

- Getting clients - seen lots out there about this but with the way the industry is set up/my contract I think I might have to wait till I'm not actually working for an agency anymore before actively looking for work. I'm hoping that my current and previous agencies will be a good source of work, plus I see specialised recruiters advertising for freelance contracts.

- Is it better to start out picky/specialised if you can, or take anything/everything until you build up a reputation? I have a reasonable cushion financially to start me off, and I'm wary of getting sucked into a particular type of work which I have experience of, but dislike doing - i don't want to become a freelancer who is known for that kind of work and so gets mainly that, given one of the reasons I want to go freelance is to avoid getting sucked into doing so much of it.
--Is it foolish or reasonable to start out trying to focus on the type of jobs I'd prefer to be doing? The type of writing jobs I dislike are probably a more common skill in my industry with more competition; the stuff I'd rather be doing is a bit more niche and I would expect fewer people to have that experience. I'm considering emphasising that skill in my profile/CV in the hope of getting more of that type of work, but unsure if that is likely to end up with a client shortage! I do want to keep a reasonably open mind to different kinds of writing opportunities - one of the things I enjoy about what I do is getting the chance to try different kinds of writing/topics.

Hope this all makes sense to freelancers in general! Would welcome any advice. I am more confident about the business/tax side having worked as contractor before in the pharma industry (though always willing to learn more); it's taking the plunge and looking for my own clients which is more intimidating at the moment.