Hello Burra Maluca: From the very first PDC, Bill Mollison said and he hasn't changed that I know of, anyone who finishes a PDC and feels confident to teach needs to go and teach. He said "You will still know more than your students". Not in every topic of course but then you have in-class teachers who are specialised students who attend..
The Diploma in Permaculture Design was originally awarded in six areas/disciplines after two years of work. So for the Education discipline, an applicant must do two years of teaching. No one has stated how much or how little that needs be. And I would make the claim that minimally teaching or co-teaching four PDCs would be necessary to ensure competence and ethics.
So now what has happened. Some of the Membership Institutes have set down pathways to a PDC. I am not sure about this but I heard that one requests 12 permaculture designs and I cannot see how this makes competence in teachers but it will give experience for those wanting to be Designers and Consultants especially if they have experience in implementation which is not usually included in a PDC - hence the growing number of bootcamps.
As for starting immediately, reputations are made by two types of teaching - either inspirational or competence based. You can think of the teachers you know who offer these. In my experience, students from inspirational teachers have some big gaps in their knowledge eg. haven't heard of or can't do a sector analysis, or water audit etc. But good students learn these afterwards when they are keen.
One student, Tamara, from my Teaching course returned home and put a sign on her gate: Free Permaculture Design Course starts here Monday for the next 12 Mondays. Then she started a free Tuesday class. Now people simply pay her. Go to the highways and byways?
The Teaching course I offer (and I am not touting for students) students how to teach in the mornings and then you prepare work from the PDC and teach in the afternoon. You write your ethics, course outcomes, students responses, Language which works and Languar Which doesn't and at the end your present a PDC outline with your group. Most students finishing these course go and teach. Some find they don't want it. It is better than the PDC for turning out teachers because the practice, and revision builds confidence and skills.
Now Portugal and perhaps Greece are special cases of having many people with PDCs and few teachers, very high unemployment of pretty educated people, needing more than the backbreaking traditional farming and they also have access to land...
So in Portugal, not wanting to import overseas/foreign teachers they feel they need to short-cut the process or that was the conversation when I was there. Barcelona has a mentoring program.
I value this diversity of options because otherwise we will choke in bureaucracy. And we want to be able to evolve for different situations as the future is unseeable.
But it means sometimes teachers are unethical. For example offer courses less than 12 days, do mud-building etc, not make mandatory attendance at the course. Some of us know these people and we would not accept their PDC students as qualified. So the community of teachers is tending to regulate and recommend.
So if you wanted to work towards a diploma, I suggest that you shop around and ask people as well. UK has a good model. Scandinavian countries use peer review which the Blue Mountains Permaculture Institute offers. This is a Meritocracy. We off them to people whose work is outstanding and we are preparing some right now to put on the web and if you think the standard is poor. Then tell us. We want to be simple and accountable and ethical and high quality.
So if you think, and the choice is yours, you need a Diploma to teach then I would recommend an organisation setting up a highly condensed mix of boot camp and deeper theory for PDC holders and then give them a Diploma. Now, if you accept money for these trainees and 12 weeks would be minimum with one topic a week in depth, then you must have a curriculum or in Australia, you can be taken to the Department of Fair Trading and go to court. You can't just take the money and get people to work as Woofers and they say they can have a Diploma. It's an ethical situation. You would need to tell students what they would learn, have a timetable and set up outcomes and ensure the balance of theory and practical is integrated.
Also have a look at Matt's website recommendation. I haven't looked at it yet but do your research. Please ask again where Im not clear but its a big topic.