Hi Sue & BJM6
To be honest, I would say that as soon as you feel able to set up in practice, then you should just go for it. There is nothing better for you, as a professional bookkeeper and trusted advisor, than gaining experience as soon as you're able to, the more the better. But you have to be ready to take on that challenge because every job (and you can bet your bottom dollar that it will be your first or second job) is not going to be textbook. Besides, you'll have a good network behind you here if you need any help and advice.
If you feel you want to wait until after ABA9, then do so, but I would have my plan in place now so that you're starting to get your network sorted out. Make sure you have access to several accountants and wealth management people, business consultants are also handy. Make sure you have your business cards and flyers designed and ready to go. Think about how you're going to attract people to you, is this going to be by website, social media, advertising, etc and have a good understanding of how to achieve this. Sort out your pricing models. Make sure you have policies in place for making decisions about prospective clients. Are you thinking aobut joining forces with someone to get a bit of experieince and see if you can subcontract for them. Get your basics set up, think about AML, GDPR, letters of engagement, etc - there are useful templates on the ICB website.
I started off working for myself, part time in an accountancy practice and going for jobs on People Per Hour. This was 6 years ago and might not be suitable any longer as there are a lot of people selling their services incredibly cheaply on PPH, I can't compete anymore on there and to be honest I don't have to (or want to as most of the people using it now want cheap). I also have a Linkedin profile that generated some clients. Most of mine now come through referrals, and I've just joined a networking group to try and garner a few more so that I can grow my business to the next level. I only lasted in the practice for 9 months, they wanted someone full time and I wouldn't work for the wage they wanted to pay me, so I used up my spare time networking and I found someone I could subcontract to. She ended up giving up her franchise and I ended up keeping the several clients I was looking after. It probably took me about 2 1/2 years to get to onsite capacity and now I'm working towards remote capacity as well so that I can then begin to field work to subcontractors (initially) and then maybe take someone on as an employee.
I hope this helps a little,
Many best wishes