I think it all depends on the area you live in- for salary and abundance of jobs. Where are you located? I am not trained, but am thinking about doing it soon- have always worked as a specialist in M schools, mom is M trained, went to M, etc. I can tell you what I have seen with others...M jobs are usually not too terribly tough to come by. In my area there are many schools and, also, keep in mind that trainees do a practicum for at least one school year, so if there were no open positions, we would have no new Montessori teachers. The training model kind of allows for some flow in staff amongst schools. I know teachers who (either after a couple of years or a couple of decades of teaching) have moved on to jobs like curriculum coordinator, admissions director, or some other type of administrative role, either in a M school or another private school.
Primary training is going to be the most flexible when it comes to finding a job because that age group makes up the bulk of M classrooms. Infant classes are few and far between- the one we had at the school where I was working was closed down. Toddler programs, however, are on the rise in this area (15 months+). I'd take a look at schools in your area and check out what/how many jobs are available this coming "season". This is assuming you want to stay in the same area.
If you're interested in opening your own infant or toddler program, I've seen people doing that, too. I followed this blog before she got her training (at the time it was one of two good, practical sources I could find about floor beds/infant montessori!) and now she has a toddler program 3 mornings a week that is run out of her home:
http://modernmontessoriaesthetic.blogspot.com/
http://www.morningsinthenest.com/Mornings_in_the_Nest/Welcome.html
Good luck.
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